Predicted to enable CD4 receptor binding activity; protein phosphatase binding activity; and sialic acid binding activity. Predicted to be involved in several processes, including negative regulation of immunoglobulin production; negative regulation of signal transduction; and regulation of B cell proliferation. Predicted to be located in cell surface and neuronal cell body membrane. Predicted to be active in early endosome; external side of plasma membrane; and recycling endosome. Human ortholog(s) of this gene implicated in diffuse large B-cell lymphoma. Orthologous to human CD22 (CD22 molecule); PARTICIPATES IN B cell receptor signaling pathway; INTERACTS WITH 17beta-estradiol; 17beta-estradiol 3-benzoate; 2,3,7,8-tetrachlorodibenzodioxine.