Involved in several processes, including B-1 B cell differentiation; positive regulation of phosphatidylinositol 3-kinase activity; and positive regulation of release of sequestered calcium ion into cytosol. Acts upstream of or within B cell receptor signaling pathway. Located in external side of plasma membrane. Is integral component of plasma membrane. Is expressed in liver and spleen. Human ortholog(s) of this gene implicated in common variable immunodeficiency. Orthologous to human CD19 (CD19 molecule).
