Sperm Protein Associated With The Nucleus, X-Linked Family, Member B1 (SPANXB1)

SPANXB1 contains 3 overlapping consensus nuclear localization signals and a potential N-glycosylation site. It shares 83.5% sequence identity with SPANXA1.Western blot analysis of transfected CV1 cells detected SPANXB at an apparent molecular mass of about 22 kD. SPANXB1, like other SPANX proteins, contains a C-terminal GAL4 (LGALS4)-like domain. PCR detected SPANXB1 only in sperm cell precursors and not in melanoma or glioblastoma cell lines.SPANXB1 was the only SPANX transcript expressed in all 9 testicular mRNA samples examined.

SPANXB1 gene contains 2 exons. SPANXB1 amplification did not appear to be linked to prostate cancer predisposition. The upstream region also contains an Alu sequence.