Molecular cloning and expression of murine homologue of semaphorin K1 gene.

We have cloned a mouse homologue of semaphorin K1 cDNA. Sequence analysis has predicted that the mouse semaphorin K1 encodes a 664 amino acid protein and contains a characteristic semaphorin domain in the N terminus followed by an immunoglobulin-like domain and a glycosylphosphatidylinositol anchoring sequence in the C terminus. In addition, this molecule has a RGD motif within the semaphorin domain. There is a high degree of amino acid identity between mouse and human semaphorin K1(89.5%). Northern blot analysis has revealed that the highest expression is detected in the nervous system and the expression level increases during neural development. Moreover, moderate expression is also detected in the immune system such as thymus and spleen. Thus, semaphorin K1 may play essential roles not only in the nervous system but also in the immune system.