A B cell specific immediate early human gene is located on chromosome band 1q31 and encodes an alpha helical basic phosphoprotein.

We have determined the cDNA sequence of a human B cell specific, immediate early gene, designated 1R20, which is inducible in response to several B cell activation signals. The cDNA sequence predicts a 196 amino acid open reading frame comprising numerous highly basic residues and the predicted structure contains several potential alpha helical domains together with eight consensus protein phosphorylation sites. The 1R20 gene has been localised by fluorescence in situ hybridisation to chromosome band 1q31, a region known to be implicated in the pathogenesis of haemopoietic malignancies.