Khatlani T S, Ma Z, Okuda M, Onishi T
Laboratory of Veterinary Internal Medicine, Faculty of Agriculture, Yamaguchi University, 1677-1 Yoshida, Yamagughi 753-8515, Japan.
Vet Immunol Immunopathol. 2001 Feb 10;78(3-4):341-8. doi: 10.1016/s0165-2427(01)00238-0.
T-cells express CD28 and CTLA-4, and through binding to their shared ligands (CD80/CD86) on antigen presenting cells, provide a potent co-stimulatory signal for T-cell activation and proliferation. To investigate the role of CD28 in canine immune system, we hereby report the molecular cloning and sequencing of the full-length complementary DNA (cDNA) coding for canine CD28, from pokeweed mitogen stimulated canine peripheral blood lymphocytes. The cloned cDNA contains an open reading frame of 663 nucleotides, encoding for a polypeptide of 221 amino acids. The amino acid sequence of the canine CD28 showed 91.9, 80, and 79.6% similarities with those of the cat, cattle, and human counterparts, respectively. Five sequence motifs of TATT or ATTTA involved in the regulation of gene expression by influencing mRNA stability are found in the 3' untranslated region. The hexapeptide motif (MYPPPY), five cysteine residues, a potential N-glycosylation site and a cytoplasmic phosphatidylinositol 3-kinase binding site in canine CD28 molecule are completely conserved in canine CTLA-4. The availability of full length canine CD28 will provide a useful molecule for studying its role in dog immune system.
T细胞表达CD28和CTLA-4，通过与抗原呈递细胞上它们的共同配体（CD80/CD86）结合，为T细胞活化和增殖提供强大的共刺激信号。为了研究CD28在犬免疫系统中的作用，我们在此报告从商陆丝裂原刺激的犬外周血淋巴细胞中克隆并测序编码犬CD28的全长互补DNA（cDNA）。克隆的cDNA包含一个663个核苷酸的开放阅读框，编码一个221个氨基酸的多肽。犬CD28的氨基酸序列与猫、牛和人类相应序列分别显示出91.9%、80%和79.6%的相似性。在3'非翻译区发现了五个TATT或ATTTA序列基序，它们通过影响mRNA稳定性参与基因表达的调控。犬CD28分子中的六肽基序（MYPPPY）、五个半胱氨酸残基、一个潜在的N-糖基化位点和一个细胞质磷脂酰肌醇3-激酶结合位点在犬CTLA-4中完全保守。全长犬CD28的可得性将为研究其在犬免疫系统中的作用提供一个有用的分子。
