BXMAS1 identifies a cluster of homologous genes differentially expressed in B cells

Characterization of genes activated by anti-IgM crosslinking of BL2 cells i dentified one gene, designated BXMAS1, that is predicted to be a novel cell surface receptor. The time course of activation indicates maximal transcri ptional induction after 24 h. The predicted protein contains 977 aa residue s, with a cytoplasmic domain containing 2 ITIM motifs. The ectodomain of th e protein contains 6 repeats of characteristic 93 aa sequences which we hav e designated BXMAS1 domains. These domains correspond to 6 out of 8 Ig-like domains in BXMAS1. A search of the human genome revealed 5 additional clos ely linked homologous genes many of which contain BXMAS1 domains as well. A nalysis of expression in cell lines and tissues suggests a general restrict ion of expression of these genes to B cells. These genes may be involved in B cell development and differentiation in peripheral lymphoid organs and m ay be useful markers of B cell stages. (C) 2001 Academic Press.