Abstract:

The objective of this study was to analyze structural feature of bovine integrin β3 and β8 subunit from molecular level, and lay foundation for understanding the interaction of FMDV with its integrin receptor during genetic variation process. We cloned β3 and β8 gene of integrin from bovine kidney by reverse transcription polymerase chain reaction (RTPCR) method and utilized biology software analyzing their molecular characteristics. The 2 355 bp cDNA of bovine integrin β3 encodes a polypeptide of 784 amino acids consisting of a 22residue putative signal peptide, a 692residue ectodomain, a 29residue transmembrane domain, and a 41residue cytoplasmic domain. The amino acid similarity of integrin β3 between cattle and ovis was the highest in compared animals, and was in the same evolution branch with animals which was suspectable to FMDV, such as cattle, camel, porcine and ovis. The conservatism of functional domain was cytoplasmic＞transmembrane＞ligandbinding domain ＞ectoplasmic ＞ signal peptide, and mutation of the cysteinerich domain in ectoplasmic was second only signal peptide. The 2 304 bp cDNA of bovine integrin β8 encodes a polypeptide of 767 amino acids consisting of a 42residue putative signal peptide, a 637residue ectodomain, a 29residue transmembrane domain, and a 59residue cytoplasmic domain. The amino acid similarity of integrin β8 between cattle and horse was the highest in compared animals, not in the same evolution branch with porcine. The conservatism of functional domain was transmembrane＞ligandbinding domain ＞cytoplasmic ＞ectoplasmic ＞ signal peptide. Ligandbinding domain of β8 was more conservative than β3, the cytoplasmic tail of β8 contained a NPLY motif, but NPXY motif was not in cytoplasmic tail of β8, and mutation of cytoplasmic tail in β8 gene was much higher than that β3 subunit. These results indicated that FMDV strains infected animals by ανβ8 receptor with much probability than ανβ3 may have relation to conservation of ligandbinding domain of β8 subunit.