Molecular cloning and expression analysis of pig CD79 alpha

Abstract

The CD79 alpha (immunoglobulin a, Iga), a part of B cell receptor (BCR) complex, forms a heterodimer with CD79 beta (Ig beta) and plays an important role in the B cell signaling. In this study, we have cloned pig Cd79a cDNA using RT-PCR and determined the complete cDNA sequence of pig Cd79a. Pig Cd79a cDNA contains an open reading frame (672 bp) encoding 223 amino acids. The putative amino acid identity of pig CD79 alpha with those of human, cattle and mouse are 70.4, 81.4, and 67.7%, respectively. Alignment of the CD79 alpha amino acid sequence with those of mammalian species showed that the extracellular domain is the most divergent, whereas transmembrane region and cytoplasmic tail including immunoreceptor tyrosine-based activation motif (ITAM) are largely conserved. Pig Cd79 alpha mRNA was detected mainly in lymphoid tissues by RT-PCR. The highest level of Cd79a mRNA expression was observed in mesenteric lymph node and spleen. Relatively low level of Cd79a mRNA expression was observed in lung, thymus and small intestine. The lowest level of Cd79a mRNA expression was observed in large intestine. Flow cytometry analyses demonstrated that human CD79 alpha antibody recognizes a CD79 alpha in pig B cells. Further, immunohistochemistry analysis using human CD79a antibody on pig spleen was revealed that CD79 alpha is strongly expressed in the follicular mantle zone rather than in the germinal center. Future study will be focused on defining the functional role of CD79 alpha during the course of pig infectious diseases and the formation of neoplasm. (c) 2008 Elsevier B.V. All rights reserved.