Molecular characterization of guinea ‐ pig (Cavia porcellus) CD8α and CD8β cDNA

Abstract

CD8 is expressed on cytotoxic T cells (CTL) and functions as a coreceptor for recognition of major histocompatibility complex (MHC) class I peptide complexes by the T-cell receptor (TCR). The CD8 molecule consists of two subunits (alpha and beta) and exists either as a heterodimer (alphabeta) or a homodimer (alphaalpha). We report the cloning of full-length cDNAs of guinea pig CD8alpha and CD8beta. The deduced amino acid sequence of CD8alpha and CD8beta reveals characteristic structural features including a signal peptide, an immunoglobulin (Ig) variable-like region, hinge region, transmembrane, and cytoplasmic domains. In addition to the full-length cDNA, a splice variant of CD8beta cDNA was observed, suggesting splicing events as reported for human CD8beta. The sequence homology of guinea pig CD8 indicates greater homology to human, canine, and feline counterparts than to rodent CD8. As the guinea pig serves as an ideal non-primate animal model to several human infectious diseases, such as syphilis, tuberculosis, and chlamydial genital and ocular infection, the CD8 sequence information provides a necessary molecular tool for studying the cell-mediated immune response.

The CD8α from sea bass (Dicentrarchus labrax L.): Cloning, expression and 3D modelling

“…2) sites have been identified in the hinge region: the sialylation of the O-linked sugar residues along with the proline residues is involved in keeping the hinge in such a configuration able to reach the domains of the MHC class I molecule [42]. A unique putative N-glycosylation site was found in sea bass CD8a, different in location to the site seen in human and squirrel monkey [44] and carp [19], and in contrast to the lack of glycosylation sites found in pig [9], trout and salmon [18,20] sequences. The transmembrane and cytoplasmic domains are the most conserved among the sequences examined in the alignment in Fig.…”

“…Both a and b chains are composed of a single N-terminal extracellular Ig superfamily (IgSf) V domain, a membrane proximal hinge region, a transmembrane domain and a C-terminal cytoplasmic tail responsible for interaction with p56 lck , the lymphocyte specific kinase [5e7]. Thymocytes and mature T lymphocytes express mainly the heterodimer CD8 molecule [8], while the homodimer is exclusively present on subsets of natural killer (NK) cells, intestinal intraepithelial lymphocytes (IEL) and a subset of dendritic cells [9].…”

Cell markers and determinants in fish immunology

“…Both a and b chains are composed of a single N-terminal extracellular Ig superfamily (IgSf) V domain, a membrane proximal hinge region, a transmembrane domain and a C-terminal cytoplasmic tail responsible for intracellular signal transduction. Thymocytes and mature T lymphocytes express mainly the heterodimer CD8 molecule [115], while the homodimer is exclusively present on subsets of natural killer (NK) cells, intestinal intraepithelial lymphocytes (IEL) and a subset of dendritic cells [116].…”

CD8α and CD8β in Atlantic halibut, Hippoglossus hippoglossus: Cloning, characterization and gene expression during viral and bacterial infection

“…This cytoplasmic tail is responsible for the association with the tyrosine kinase p56 lck during signal transduction [1,2]. The heterodimer is expressed mainly by thymocytes and mature Tc-cells [3], while only the homodimer is present on subsets of natural killer (NK) cells, TCRg/d cells in the gut [4,5], intestinal intraepithelial lymphocytes (IEL) [6], and subsets of dendritic cells [7,8] and monocytes [9]. Since most Tc-cells express CD8, it is a useful marker to investigate their role in immune responses.…”