NEW EUKARYOTIC SEMAPHORINS WITH CLOSE HOMOLOGY TO SEMAPHORINS OF DNA VIRUSES

Semaphorins were initially described as a family of repulsive guidance molecules in embryonal development. Their basic structure consists of an N-terminal signal sequence, the defining semaphorin domain of appr oximately 500 amino acids, an Ig-like domain, and a variable carboxy-t erminus. We recently described a viral semaphorin homologue encoded by the alcelaphine herpesvirus type 1. Less conserved, truncated homolog ues were also identified in poxviruses. Here we describe new human and murine semaphorin homologues. The respective genes were cloned and se quenced, and they were termed H-Sema-L and M-Sema-L (HGMW-approved sym bols SEMAL and Semal, respectively). A multiply spliced mRNA of 3.2 kb is expressed in human placenta, spleen, thymus, and gonadal tissue. H -Sema-L maps to chromosome 15q22.3-q23 and M-Sema-L to the homologous locus 9A3.3-B in the mouse genome. The expression patterns and the pre sence of related genes in large DNA viruses suggest that this new sema phorin has a relevant function in the immune system. (C) 1998 Academic Press