Poly A Binding Protein Cytoplasmic 3 (PABPC3)

PABPC3 is an intronless gene. Sequence analysis of the promoter region revealed binding sites for AP4, AP2, and NF1, as well as an myb element and a Gf1 transcriptional repressor site.

The deduced 631-amino acid protein has 4 RNA-binding domains, each of which contains 2 ribonucleoprotein consensus motifs, and shares 92.5% sequence identity with PABPC1. By Northern blot analysis of multiple tissues, Feral et al. (2001) found testis-specific expression of 2 weak but distinct bands of 2.1 and 2.5 kb. The 2 transcripts may reflect use of one of the 3 alternative polyadenylation signals. In situ hybridization showed that expression is restricted to round spermatids of the testis. By Western blot analysis, the protein has an apparent molecular mass of 70 kD.