Molecular cloning characterization and expression of porcine immunoreceptor SIRPalpha.
SWC3 is a porcine CD that has been the reference marker of myeloid lineage. It is expressed in every myelomonocytic cell from early bone marrow precursors. We have identified the molecule recognized by anti-SWC3 antibodies as a member of the signal-regulatory proteins (SIRPs)alpha family. Here, we describe the cloning of a cDNA coding for a porcine SIRPalpha protein. The sequence is 2470 nucleotides long and contains an open reading frame encoding a 507 amino acid sequence. The predicted polypeptide was composed of a 30 amino acids putative signal peptide, a 342 amino acid extracellular region, a 23 amino acid transmembrane segment and a 112 amino acid cytoplasmic domain. Analysis of the sequence reveals a high degree of homology with known SIRPs in other species, being easily identified the three extracellular Ig type domains and two cytoplasmic ITIM motifs characteristic of this molecule. The gene coding for porcine SIRPalpha has been mapped to porcine chromosome 17, in a region syntenic to the human chromosome 20 where SIRP genes have been mapped. During the analysis of SIRP gene expression in tissues by RT-PCR, we noticed the existence of a shorter mRNA, and cloned the corresponding cDNA. This coded for a splicing variant of SIRPalpha that lacked the two membrane proximal Ig domains. In transfection experiments, we have been able to show that anti-SWC3 antibodies recognize both forms of the molecule, mapping the SWC3 epitopes to the N-terminal IgV type domain.
Alvarez
Belén
B
Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain.
Gómez
Nuria
N
José Garrido
Juan
J
Yerle
Martine
M
Revilla
Concepción
C
Chamorro
Sonia
S
Alonso
Fernando
F
Domínguez
Javier
J
Ezquerra
Angel
A
D000818:Animals; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D015870:Gene Expression; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D011971:Receptors, Immunologic / Q000235:genetics*; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D013552:Swine
D015214:Antigens, Differentiation, Myelomonocytic; D011971:Receptors, Immunologic