biostudies-literatureJia ZScience and Technology Program of Hunan ProvinceNational Natural Science Foundation of China1156219https://www.ebi.ac.uk/biostudies/studies/S-EPMC10140343biostudies-literatureUnknown14<h4>Introduction</h4>Cartilaginous fishes are the most evolutionary-distant vertebrates from mammals and possess an immunoglobulin (Ig)- and T cell-mediated adaptive immunity. CD8 is the hallmark receptor of cytotoxic T cells and is required for the formation of T cell receptor-major histocompatibility complex (TCR-MHC) class I complexes.<h4>Methods</h4>RACE PCR was used to obtain gene sequences. Direct dilution was applied for the refolding of denatured recombinant CD8 protein. Hanging-drop vapor diffusion method was performed for protein crystallization.<h4>Results</h4>In this study, CD8α and CD8β orthologues (termed ScCD8α and ScCD8β) were identified in small-spotted catshark (<i>Scyliorhinus canicula</i>). Both ScCD8α and ScCD8β possess an extracellular immunoglobulin superfamily (IgSFFrontiers in immunologyThe first crystal structure of CD8αα from a cartilaginous fish.PMC1014034332030112 , U21A20268Zou JFeng JDooley HWang JJia ZfalseThe first crystal structure of CD8αα from a cartilaginous fish.<h4>Introduction</h4>Cartilaginous fishes are the most evolutionary-distant vertebrates from mammals and possess an immunoglobulin (Ig)- and T cell-mediated adaptive immunity. CD8 is the hallmark receptor of cytotoxic T cells and is required for the formation of T cell receptor-major histocompatibility complex (TCR-MHC) class I complexes.<h4>Methods</h4>RACE PCR was used to obtain gene sequences. Direct dilution was applied for the refolding of denatured recombinant CD8 protein. Hanging-drop vapor diffusion method was performed for protein crystallization.<h4>Results</h4>In this study, CD8α and CD8β orthologues (termed ScCD8α and ScCD8β) were identified in small-spotted catshark (<i>Scyliorhinus canicula</i>). Both ScCD8α and ScCD8β possess an extracellular immunoglobulin superfamily (IgSF2023-01-01T00:00:00Z20232026-05-29T02:23:39.362Z2025-02-19T02:23:59.56ZS-EPMC101403433712269710.3389/fimmu.2023.1156219