title: A dimeric structure of PD-L1: functional units or evolutionary relics?
abstract: PD-L1 is a member of the B7 protein family, most of whose members so far were identified as dimers in a solution and crystalline state, either complexed or uncomplexed with their ligand(s). The binding of PD-L1 with its receptor PD-1 (CD279) delivers an inhibitory signal regulating the T cell function. Simultaneously with the Garboczi group, we successfully solved another structure of human PD-L1 (hPD-L1). Our protein crystallized in the space group of C222(1) with two hPD-L1 molecules per asymmetric unit. After comparison of reported B7 structures, we have found some intrinsic factors involved in the interaction of these two molecules. Based on these results, we tend to believe this uncomplexed hPD-L1 structure demonstrated its potential dimeric state in solution, although it could just be an evolutionary relic, too weak to be detected under present technology, or still a functional unit deserved our attentions.
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CASPMI), Beijing 100101, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Peipei
authors.initials: P
authors.lastname: Liu
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Hao
authors.initials: H
authors.lastname: Cheng
authors.forename: Jianxun
authors.initials: J
authors.lastname: Qi
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
mesh_terms: D015703:Antigens, CD / Q000737:chemistry* / Q000276:immunology*; D060890:B7-H1 Antigen; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D006801:Humans; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D013601:T-Lymphocytes / Q000737:chemistry / Q000276:immunology
chemical_list: D015703:Antigens, CD; D060890:B7-H1 Antigen; C423236:CD274 protein, human