Cheng X, Veverka V, Radhakrishnan A, Waters LC, Muskett FW, Morgan SH, Huo J, Yu C, Evans EJ, Leslie AJ, Griffiths M, Stubberfield C, Griffin R, Henry AJ, Jansson A, Ladbury JE, Ikemizu S, Carr MD, Davis SJ (2013), J Biol Chem. 288, 11771-85
We were among the first groups to consider the problem of how recognition at the cell surface can be both weak and specific, and perhaps the first to emphasize its novel features.
To understand how cells interact it’s helpful to know in detail the structures and interactions of the proteins involved. Our success in this work depended entirely on our ability to make first-class soluble T-cell surface proteins. For this we have to thank having access to the glutamine synthetase-based gene expression system, and expert training in the use of the system by Prof Neil Barclay at what was then the MRC Cellular Immunology Unit.
To understand how cells interact it’s helpful to know the structures and interactions of the proteins involved. SJD went to Oxford initially to help determine the structure of the AIDS virus receptor, CD4. Alan Williams had argued that because protein crystallization was unpredictable several species should be tried in case human CD4 was especially difficult. We started work on rat CD4 and published the first (problematic) crystals, but the first structure to be solved comprised the N-terminal two domains of human CD4 by the groups of Steve Harrison and Wayne Hendrickson. The work on multiple species was vindicated; it just hadn’t worked in our favour.
We had tried the N-terminal two domains of rat CD4 also, and a crucial difference was that the rat protein carried a domain 2 N-glycan and it wouldn’t crystallize. This prompted us to try to solve the “glycosylation problem”, i.e. the need to deglycosylate glycoproteins of crystallographic interest. Glycosylation is an issue for crystallization studies because “normal” N-glycans are large, flexible and extremely heterogeneous and therefore work against the formation of reproducible lattice contacts in crystals. We chose the general approach of deglycosylating the protein of interest after we had purified it (1) because co-translational glycosylation is often required in order for proteins to fold correctly in mammalian cells in the first instance and because we had made a large commitment to mammalian expression (2).
We generated deglycosylatable forms of glycoproteins by arresting the processing of the N-glycans at an endoglycosidase (Endo) H- or Endo F1-sensitive, largely oligomannose stage using lectin-resistant Chinese hamster ovary (CHO)-derived cell lines deficient (most importantly) in UDP-N-acetyl-d-glucosamine:α-3-d-mannosidase β1,2-N-acetylglucosaminyltransferase I (e.g. Lec18.104.22.168 cells), or by adding the α-glucosidase I inhibitor N-butyldeoxynojirimycin to CHO cell cultures expressing our proteins. This idea emerged after we learnt that one of the chief (perhaps only) advantages of insect-cell expression is that insect cells add fairly simple, relatively easily removed N-glycans to proteins. The first protein for which the new mammalian cell-based method was tried was rat CD2 (four N-glycans distributed over two domains), which produced beautiful crystals in the first hanging-drop we set up after expressing the protein in Lec22.214.171.124 cells and digesting it with Endo H (1) (Fig. 1).
We have found that the polydispersity in solution of most Endo H/F1 treated proteins is indistinguishable from that of wild-type proteins, whereas glycoproteins completely deglycosylated with, for example, PNGase F, tend to aggregate. We subsequently developed tools (3) for producing deglycosylatable proteins in transient mammalian expression systems based on human embryonic kidney 293T cells, using the alkaloids kifunensine and swainsonine, which are inhibitors of α-mannosidases I and II, respectively. This coincided with great improvements in the yields, efficiency and scalability of transient expression protocols owing to the advent of new episomal expression vectors, transfection protocols and the introduction of a cheap transfection reagent, polyethylenimine, together with the development of multiplex, deep-well tissue culture methods. These types of methods are now widely used in glycoprotein crystallography.
Access to the structures and to surface plasmon resonance-based assay (Biacore™) technology then allowed us to get at the problem of how low-affinity, high-specificity recognition is achieved at the cell surface. Our early work on CD2 based on the rat CD2 structure highlighted the importance of charged residues (4) (Fig. 2). We then determined the crystal structure of the ligand-binding domain of the CD2 ligand, CD48, and characterized its interactions with CD2 and 2B4. The relatively simple arrangement of charged residues on the flat binding face of CD48 seems ideally suited to binding multiple ligands, while maintaining low affinity for each of them. We speculated that cross-reactive interactions of this type fuelled the initial expansion of CD2-related genes. Overall, the data suggest that the evolutionary diversification of interacting cell surface proteins is rapid, and constrained only by the requirement that binding is weak and specific.
Our structures of the costimulatory receptor CD28 (5) and ligand CD80 (6) completed the initial structural analysis of the costimulatory system, and offered explanations for several important functional similarities and differences between CD28 and CTLA-4. In particular, it explained the unexpected finding that CD28 is monovalent, which in turn emphasized the importance of the very strong inhibitory interactions of CTLA-4, which is bivalent. The core of the ligand binding sites of CD28 and CTLA-4 and the conformation of the MYPPPY motifs proved to be highly conserved, implying that very subtle conformational differences underly the 8- to 40-fold variation in their affinities for each of their ligands, CD80 and CD86. Other structural comparisons redefined the evolutionary relationships of CD28-related proteins, antigen receptors and adhesion molecules. Most recently, Biacore™ analysis of PD-1/ligand interactions (7) established the biophysical basis of check-point inhibition and pointed to the ostensibly redundant role of PD-L2.
Fig. 1: Deglycosylation and crystallization of sCD2
(A) The soluble CD2 expressed in the Lec126.96.36.199 cell line was treated with endoglycosidase H and purified by Sephadex G-75 gel-filtration. The starting material (4 μg, lane 2) and deglycosylated sCD2 (4 μg, lane 3) were then analysed on a 15% SDS-Page gel run under reducing conditions and then stained with Coomassie blue. For comparison sCD2 expressed in CHO-K1 cells was also run (4 μg, lane 1). (B) The deglycosylated sCD2 was concentrated and subjected to hanging-drop, vapour-diffusion crystallization trials in the presence of 15-18% polyethylene glycol (Mr = 4000). Typical crystals are shown; the largest crystals grew to 0.3 × 0.08 × 0.08 mm.
Fig. 2: Mutagenesis of domain 1 of CD2
The crystal structure of domain 1 of CD2 (residues 1–99) is shown in Corey, Pauling, and Koltun format drawn using RASMOL. In each panel, the view is approximately perpendicular to the ligand-binding GFCC′C” β-sheet surface. (A) Residues whose nonconservative substitution significantly interfered with, or had no effect on, ligand (CD48) binding by CD2 are colored red and light blue, respectively. All of the unmutated residues are colored yellow, except for the sites ofN-glycosylation (N67, N77, and N84) which are colored green. (B) The chemical composition of domain 1 of CD2 is indicated by coloring acidic residues red, basic residues dark blue, uncharged polar residues light blue, and hydrophobic residues green. (C) Residues whose substitution with alanine reduced ligand-binding affinity >20-fold are colored red and those for which the reduction in affinity was twofold or less are colored light blue. The details of the substitutions, and their effects, are given in (4).
- Davis SJ, Puklavec MJ, Ashford DA, Harlos K, Jones EY, Stuart DI, Williams AF. (1993) Expression of soluble recombinant glycoproteins with predefined glycosylation: application to the crystallization of the T-cell glycoprotein CD2. Protein Eng. 6, 229-32.
- Davis SJ, Ward HA, Puklavec MJ, Willis AC, Williams AF, Barclay AN. (1990) High level expression in Chinese hamster ovary cells of soluble forms of CD4 T lymphocyte glycoprotein including glycosylation variants. J Biol Chem. 265, 10410-8.
- Chang VT, Crispin M, Aricescu AR, Harvey DJ, Nettleship JE, Fennelly JA, Yu C, Boles KS, Evans EJ, Stuart DI, Dwek RA, Jones EY, Owens RJ, Davis SJ. (2007) Glycoprotein structural genomics: solving the glycosylation problem. Structure. 15, 267-73.
- Davis SJ, Davies EA, Tucknott MG, Jones EY, van der Merwe PA. (1998) The role of charged residues mediating low affinity protein-protein recognition at the cell surface by CD2. Proc Natl Acad Sci U S A. 95, 5490-4.
- Evans EJ, Esnouf RM, Manso-Sancho R, Gilbert RJ, James JR, Yu C, Fennelly JA, Vowles C, Hanke T, Walse B, Hünig T, Sørensen P, Stuart DI, Davis SJ. (2005) Crystal structure of a soluble CD28-Fab complex. Nat Immunol. 6, 271-9.
- Ikemizu S, Gilbert RJ, Fennelly JA, Collins AV, Harlos K, Jones EY, Stuart DI, Davis SJ. (2000) Structure and dimerization of a soluble form of B7-1. Immunity. 12, 51-60.
- Cheng X, Veverka V, Radhakrishnan A, Waters LC, Muskett FW, Morgan SH, Huo J, Yu C, Evans EJ, Leslie AJ, Griffiths M, Stubberfield C, Griffin R, Henry AJ, Jansson A, Ladbury JE, Ikemizu S, Carr MD, Davis SJ. (2013) Structure and interactions of the human programmed cell death 1 receptor. J Biol Chem. 288, 11771-85.
Protein Interaction Papers
Knox R, Nettleship JE, Chang VT, Hui ZK, Santos AM, Rahman N, Ho LP, Owens RJ, Davis SJ. (2013), BMC Biotechnol. 13, 74
T cell receptors are structures capable of initiating signaling in the absence of large conformational rearrangements
Fernandes RA, Shore DA, Vuong MT, Yu C, Zhu X, Pereira-Lopes S, Brouwer H, Fennelly JA, Jessup CM, Evans EJ, Wilson IA, Davis SJ. (2012), J Biol Chem. 287, 13324-35
Davis SJ, Crispin MD. (2011), In Functional and Structural Proteomics of Glycoproteins, RJ Owens, JE Nettleship, eds. (Netherlands: Springer)
Yu C, Sonnen AF, George R, Dessailly BH, Stagg LJ, Evans EJ, Orengo CA, Stuart DI, Ladbury JE, Ikemizu S, Gilbert RJ, Davis SJ. (2011), J Biol Chem. 286, 6685-96
An early HIV mutation within an HLA-B*57-restricted T cell epitope abrogates binding to the killer inhibitory receptor 3DL1
Brackenridge S, Evans EJ, Toebes M, Goonetilleke N, Liu MK, di Gleria K, Schumacher TN, Davis SJ, McMichael AJ, Gillespie GM. (2011), J Virol. 85, 5415-22
Use of the α-mannosidase I inhibitor kifunensine allows the crystallization of apo CTLA-4 homodimer produced in long-term cultures of Chinese hamster ovary cells
Yu C, Crispin M, Sonnen AF, Harvey DJ, Chang VT, Evans EJ, Scanlan CN, Stuart DI, Gilbert RJ, Davis SJ. (2011), Acta Crystallogr Sect F Struct Biol Cryst Commun. 67, 785-9
Jansson A, Davis SJ. (2011), Mol Immunol. 49, 527-36
Sonnen AF, Yu C, Evans EJ, Stuart DI, Davis SJ, Gilbert RJ. (2010), J Mol Biol. 399, 207-13
Crispin M, Chang VT, Harvey DJ, Dwek RA, Evans EJ, Stuart DI, Jones EY, Lord JM, Spooner RA, Davis SJ. (2009), J Biol Chem. 284, 21684-95
Molecular cloning and analysis of SSc5D, a new member of the scavenger receptor cysteine-rich superfamily
Gonçalves CM, Castro MA, Henriques T, Oliveira MI, Pinheiro HC, Oliveira C, Sreenu VB, Evans EJ, Davis SJ, Moreira A, Carmo AM. (2009), Mol Immunol. 46, 2585-96
Analysis of variable N-glycosylation site occupancy in glycoproteins by liquid chromatography electrospray ionization mass spectrometry
Nettleship JE, Aplin R, Aricescu AR, Evans EJ, Davis SJ, Crispin M, Owens RJ. (2007), Anal Biochem. 361, 149-51
The contribution of conformational adjustments and long-range electrostatic forces to the CD2/CD58 interaction
Kearney A, Avramovic A, Castro MA, Carmo AM, Davis SJ, van der Merwe PA. (2007), J Biol Chem. 282, 13160-6
Chang VT, Crispin M, Aricescu AR, Harvey DJ, Nettleship JE, Fennelly JA, Yu C, Boles KS, Evans EJ, Stuart DI, Dwek RA, Jones EY, Owens RJ, Davis SJ. (2007), Structure. 15, 267-73
Crispin M, Aricescu AR, Chang VT, Jones EY, Stuart DI, Dwek RA, Davis SJ, Harvey DJ. (2007), FEBS Lett. 581, 1963-8
Chirifu M, Hayashi C, Nakamura T, Toma S, Shuto T, Kai H, Yamagata Y, Davis SJ, Ikemizu S. (2007), Nat Immunol. 8, 1001-7
Aricescu AR, Siebold C, Choudhuri K, Chang VT, Lu W, Davis SJ, van der Merwe PA, Jones EY. (2007), Science. 317, 1217-20
Inhibition of hybrid- and complex-type glycosylation reveals the presence of the GlcNAc transferase I-independent fucosylation pathway
Crispin M, Harvey DJ, Chang VT, Yu C, Aricescu AR, Jones EY, Davis SJ, Dwek RA, Rudd PM. (2006), Glycobiology. 16, 748-56
Evans EJ, Castro MA, O’Brien R, Kearney A, Walsh H, Sparks LM, Tucknott MG, Davies EA, Carmo AM, van der Merwe PA, Stuart DI, Jones EY, Ladbury JE, Ikemizu S, Davis SJ. (2006), J Biol Chem. 281, 29309-20
Aricescu AR, Assenberg R, Bill RM, Busso D, Chang VT, Davis SJ, Dubrovsky A, Gustafsson L, Hedfalk K, Heinemann U, Jones IM, Ksiazek D, Lang C, Maskos K, Messerschmidt A, Macieira S, Peleg Y, Perrakis A, Poterszman A, Schneider G, Sixma TK, Sussman JL, Sutton G, Tarboureich N, Zeev-Ben-Mordehai T, Jones EY. (2006), Acta Crystallogr D Biol Crystallogr. 62, 1114-24
Jansson A, Barnes E, Klenerman P, Harlén M, Sørensen P, Davis SJ, Nilsson P. (2005), J Immunol. 175, 1575-85
Evans EJ, Esnouf RM, Manso-Sancho R, Gilbert RJ, James JR, Yu C, Fennelly JA, Vowles C, Hanke T, Walse B, Hünig T, Sørensen P, Stuart DI, Davis SJ. (2005), Nat Immunol. 6, 271-9
A procedure for setting up high-throughput nanolitre crystallization experiments. II. Crystallization results
Brown J, Walter TS, Carter L, Abrescia NG, Aricescu AR, Batuwangala TD, Bird LE, Brown N, Chamberlain PP, Davis SJ, Dubinina E, Endicott J, Fennelly JA, Gilbert RJ, Harkiolaki M, Hon WC, Kimberley F, Love CA, Mancini EJ, Manso-Sancho R, Nichols CE, Robinson RA, Sutton GC, Schueller N, Sleeman MC, Stewart-Jones GB, Vuong M, Welburn J, Zhang Z, Stammers DK, Owens RJ, Jones EY, Harlos K, Stuart DI. (2003), J Appl Cryst. 36, 315-8
Davis SJ, Ikemizu S, Evans EJ, Fugger L, Bakker TR, van der Merwe PA. (2003), Nat Immunol. 4, 217-24
van der Merwe PA, Davis SJ. (2003), Annu Rev Immunol. 21, 659-84
Merry AH, Gilbert RJ, Shore DA, Royle L, Miroshnychenko O, Vuong M, Wormald MR, Harvey DJ, Dwek RA, Classon BJ, Rudd PM, Davis SJ. (2003), J Biol Chem. 278, 27119-28
The ligand-binding face of the semaphorins revealed by the high-resolution crystal structure of SEMA4D
Love CA, Harlos K, Mavaddat N, Davis SJ, Stuart DI, Jones EY, Esnouf RM. (2003), Nat Struct Biol. 10, 843-8
Wheeler SF, Rudd PM, Davis SJ, Dwek RA, Harvey DJ. (2002), Glycobiology. 12, 261-71
Collins AV, Brodie DW, Gilbert RJ, Iaboni A, Manso-Sancho R, Walse B, Stuart DI, van der Merwe PA, Davis SJ. (2002), Immunity. 17, 201-10
Ikemizu S, Jones EY, Stuart DI, Davis SJ. (2001), In Activating and Inhibitory Immunoglobulin-like Receptors, MD Cooper, T Takai, JV Ravetch, eds. (Japan: Springer)
Crystallization and functional analysis of a soluble deglycosylated form of the human costimulatory molecule B7-1
Davis SJ, Ikemizu S, Collins AV, Fennelly JA, Harlos K, Jones EY, Stuart DI. (2001), Acta Crystallogr D Biol Crystallogr. 57, 605-8
Stamper CC, Zhang Y, Tobin JF, Erbe DV, Ikemizu S, Davis SJ, Stahl ML, Seehra J, Somers WS, Mosyak L. (2001), Nature. 410, 608-11
Fennelly JA, Tiwari B, Davis SJ, Evans EJ. (2001), Immunogenetics. 53, 599-602
Bromley SK, Iaboni A, Davis SJ, Whitty A, Green JM, Shaw AS, Weiss A, Dustin ML. (2001), Nat Immunol. 2, 1159-66
Signaling lymphocytic activation molecule (CDw150) is homophilic but self-associates with very low affinity
Mavaddat N, Mason DW, Atkinson PD, Evans EJ, Gilbert RJ, Stuart DI, Fennelly JA, Barclay AN, Davis SJ, Brown MH. (2000), J Biol Chem. 275, 28100-9
Distinct pathways of mannan-binding lectin (MBL)- and C1-complex autoactivation revealed by reconstitution of MBL with recombinant MBL-associated serine protease-2
Vorup-Jensen T, Petersen SV, Hansen AG, Poulsen K, Schwaeble W, Sim RB, Reid KB, Davis SJ, Thiel S, Jensenius JC. (2000), J Immunol. 165, 2093-100
Expression and purification of antigenically active soluble derivatives of the heterodimeric and homodimeric forms of the mouse CD8 lymphocyte membrane glycoprotein
Pellicci DG, Kortt AA, Sparrow LG, Hudson PJ, Sorensen HV, Davis SJ, Classon BJ. (2000), J Immunol Methods. 246, 149-63
Brodie D, Collins AV, Iaboni A, Fennelly JA, Sparks LM, Xu XN, van der Merwe PA, Davis SJ. (2000), Curr Biol. 10, 333-6
Ikemizu S, Gilbert RJ, Fennelly JA, Collins AV, Harlos K, Jones EY, Stuart DI, Davis SJ. (2000), Immunity. 12, 51-60
T cell receptor and coreceptor CD8 alphaalpha bind peptide-MHC independently and with distinct kinetics
Wyer JR, Willcox BE, Gao GF, Gerth UC, Davis SJ, Bell JI, van der Merwe PA, Jakobsen BK. (1999), Immunity. 10, 219-25
Crystal structure of the CD2-binding domain of CD58 (lymphocyte function-associated antigen 3) at 1.8-Å resolution
Ikemizu S, Sparks LM, van der Merwe PA, Harlos K, Stuart DI, Jones EY, Davis SJ. (1999), Proc Natl Acad Sci U S A. 96, 4289-94
Oligosaccharide analysis and molecular modeling of soluble forms of glycoproteins belonging to the Ly-6, scavenger receptor, and immunoglobulin superfamilies expressed in Chinese hamster ovary cells
Rudd PM, Wormald MR, Harvey DJ, Devasahayam M, McAlister MS, Brown MH, Davis SJ, Barclay AN, Dwek RA. (1999), Glycobiology. 9, 443-58
Effects of N-butyldeoxynojirimycin and the Lec188.8.131.52 mutant phenotype on N-glycan processing in Chinese hamster ovary cells: application to glycoprotein crystallization
Butters TD, Sparks LM, Harlos K, Ikemizu S, Stuart DI, Jones EY, Davis SJ. (1999), Protein Sci. 8, 1696-701
Rudd PM, Morgan BP, Wormald MR, Harvey DJ, van den Berg CW, Davis SJ, Ferguson MA, Dwek RA. (1998), Adv Exp Med Biol. 435, 153-62
Davis SJ, Ikemizu S, Wild MK, van der Merwe PA. (1998), Immunol Rev. 163, 217-36
Rudd PM, Morgan BP, Wormald MR, Harvey DJ, van den Berg CW, Davis SJ, Ferguson MA, Dwek RA. (1997), Biochem Soc Trans. 25, 1177-84
Characterisation of the low affinity interaction between rat cell adhesion molecules CD2 and CD48 by analytical ultracentrifugation
Silkowski H, Davis SJ, Barclay AN, Rowe AJ, Harding SE, Byron O. (1997), Eur Biophys J. 25, 455-62
van der Merwe PA, Bodian DL, Daenke S, Linsley P, Davis SJ. (1997), J Exp Med. 185, 393-403.
Mutational analysis of the active site and antibody epitopes of the complement-inhibitory glycoprotein, CD59
Bodian DL, Davis SJ, Morgan BP, Rushmere NK. (1997), J Exp Med. 185, 507-16
Rudd PM, Morgan BP, Wormald MR, Harvey DJ, van den Berg CW, Davis SJ, Ferguson MA, Dwek RA. (1997), J Biol Chem. 272, 7229-44
McAlister MS, Mott HR, van der Merwe PA, Campbell ID, Davis SJ, Driscoll PC. (1996), Biochemistry. 35, 5982-91
Davis SJ, van der Merwe PA. (1996), Science. 273, 1241-2
Davis SJ, van der Merwe PA. (1996), Immunol Today. 17, 177-87
Mutational analysis of the epitopes recognized by anti-(rat CD2) and anti-(rat CD48) monoclonal antibodies
Davis SJ, Davies EA, van der Merwe PA. (1995), Biochem Soc Trans. 23, 188-94
Topology of the CD2-CD48 cell-adhesion molecule complex: implications for antigen recognition by T cells
van der Merwe PA, McNamee PN, Davies EA, Barclay AN, Davis SJ. (1995), Curr Biol. 5, 74-84
Ligand binding by the immunoglobulin superfamily recognition molecule CD2 is glycosylation-independent
Davis SJ, Davies EA, Barclay AN, Daenke S, Bodian DL, Jones EY, Stuart DI, Butters TD, Dwek RA, van der Merwe PA. (1995), J Biol Chem. 270, 369-75
Estimation of the dissociation constant of the cell adhesion molecules srCD2 and srCD48 using analytical ultracentrifugation
Silkowski H, Byron O, Davis SJ, Barclay AN, Davies EA, Rowe AJ, Harding SE. (1995), Biochem Soc Trans. 23, 435S
The alpha-glucosidase inhibitor N-butyldeoxynojirimycin inhibits human immunodeficiency virus entry at the level of post-CD4 binding
Fischer PB, Collin M, Karlsson GB, James W, Butters TD, Davis SJ, Gordon S, Dwek RA, Platt FM. (1995), J Virol. 69, 5791-7
Expression cloning of an equine T-lymphocyte glycoprotein CD2 cDNA. Structure-based analysis of conserved sequence elements
Tavernor AS, Kydd JH, Bodian DL, Jones EY, Stuart DI, Davis SJ, Butcher GW. (1994), Eur J Biochem. 219, 969-76
Three-dimensional solution structure of the extracellular region of the complement regulatory protein CD59, a new cell-surface protein domain related to snake venom neurotoxins
Kieffer B, Driscoll PC, Campbell ID, Willis AC, van der Merwe PA, Davis SJ. (1994), Biochemistry. 33, 4471-82
Crystal structure of the extracellular region of the human cell adhesion molecule CD2 at 2.5 Å resolution
Bodian DL, Jones EY, Harlos K, Stuart DI, Davis SJ. (1994), Structure. 2, 755-66
Human cell-adhesion molecule CD2 binds CD58 (LFA-3) with a very low affinity and an extremely fast dissociation rate but does not bind CD48 or CD59
van der Merwe PA, Barclay AN, Mason DW, Davies EA, Morgan BP, Tone M, Krishnam AK, Ianelli C, Davis SJ. (1994), Biochemistry. 33, 10149-60
van der Merwe PA, Brown MH, Davis SJ, Barclay AN. (1993), Biochem Soc Trans. 21, 340S
Davis SJ, Jones EY, Bodian DL, Barclay AN, van der Merwe PA. (1993), Biochem Soc Trans. 21, 952-8
Davis SJ. (1993), Nature. 361, 212
Site-specific glycosylation of recombinant rat and human soluble CD4 variants expressed in Chinese hamster ovary cells
Ashford DA, Alafi CD, Gamble VM, Mackay DJ, Rademacher TW, Williams PJ, Dwek RA, Barclay AN, Davis SJ, Somoza C, Ward HA, Williams AF. (1993), J Biol Chem. 268, 3260-7
A rat CD4 mutant containing the gp120-binding site mediates human immunodeficiency virus type 1 infection
Simon JH, Somoza C, Schockmel GA, Collin M, Davis SJ, Williams AF, James W. (1993), J Exp Med. 177, 949-54
Brady RL, Dodson EJ, Dodson GG, Lange G, Davis SJ, Williams AF, Barclay AN. (1993), Science. 260, 979-83
The NH2-terminal domain of rat CD2 binds rat CD48 with a low affinity and binding does not require glycosylation of CD2
van der Merwe PA, McPherson DC, Brown MH, Barclay AN, Cyster JG, Williams AF, Davis SJ. (1993), Eur J Immunol. 23, 1373-7
Dwek RA, Ashford DA, Edge CJ, Parekh RB, Rademacher TW, Wing DR, Barclay AN, Davis SJ, Williams AF. (1993), Philos Trans R Soc Lond B Biol Sci. 342, 43-50
Barclay AN, Brady RL, Davis SJ, Lange G. (1993), Philos Trans R Soc Lond B Biol Sci. 342, 7-12
Davis SJ, James WS, Schockmel GA, Simon JH, Somoza C. (1993), Philos Trans R Soc Lond B Biol Sci. 342, 75-81
van der Merwe PA, Brown MH, Davis SJ, Barclay AN. (1993), EMBO J. 12, 4945-54
Schockmel GA, Somoza C, Davis SJ, Williams AF, Healey D. (1992), J Exp Med. 175, 301-4
Antibody and HIV-1 gp120 recognition of CD4 undermines the concept of mimicry between antibodies and receptors
Davis SJ, Schockmel GA, Somoza C, Buck DW, Healey DG, Rieber EP, Reiter C, Williams AF. (1992), Nature. 358, 76-9
Jones EY, Davis SJ, Williams AF, Harlos K, Stuart DI. (1992), Nature. 360, 232-9
Beyers AD, Davis SJ, Cantrell DA, Izquierdo M, Williams AF. (1991), EMBO J. 10, 377-85
Crystallization of a soluble form of the rat T-cell surface glycoprotein CD4 complexed with Fab from the W3/25 monoclonal antibody
Davis SJ, Brady RL, Barclay AN, Harlos K, Dodson GG, Williams AF. (1990), J Mol Biol. 213, 7-10
High level expression in Chinese hamster ovary cells of soluble forms of CD4 T lymphocyte glycoprotein including glycosylation variants
Davis SJ, Ward HA, Puklavec MJ, Willis AC, Williams AF, Barclay AN. (1990), J Biol Chem. 265, 10410-8
Williams AF, Davis SJ, He Q, Barclay AN. (1989), Cold Spring Harb Symp Quant Biol. 54, 637-47