DARPP-32 gene is located at 17q12. Both full length DARPP-32 and its transcriptional splice variant (t-DARPP) consist of seven exons where only exon 1 is unique in each of the two transcripts.

2 alternative transcripts

Unknown

DARPP-32 encodes a protein of 204 amino acids (about 32 kD), whereas t-DARPP encodes a 168 amino acid protein (about 28 kD). DARPP-32 contains four phosphorylation sites at Thr34, Thr75, Ser102, and Ser137, whereas t-DARPP lacks the Thr34 phosphorylation site of DARPP-32. The schematic illustration, shown above, demonstrates the phosphorylation sites of DARPP-32 and t-DARPP shown in yellow color.

DARPP-32 protein is highly expressed in medium-sized spiny neurons of the neostriatum. DARPP-32 was characterized as a major target for dopamine and protein kinase A signaling. Modulation of DARPP-32 phosphorylation state provides a molecular mechanism for integrating signals through several neurotransmitters and steroid hormones that stimulate dopaminoceptic neurons in various regions of the brain. Activation of PKA or PKG leads to phosphorylation of DARPP-32 at Thr34 and subsequently converts DARPP-32 into a potent inhibitor of protein phosphatase-1 (PP-1). Cdk5 can also phosphorylate DARPP-32 at Thr75 and this converts DARPP-32 into a PKA inhibitor. Expression of t-DARPP in the brain was not reported.
Protein and mRNA expression of both DARPP-32 and t-DARPP are expressed at varying levels in several types of normal epithelial tissues outside the brain. DARPP-32 and t-DARPP are over-expressed in carcinomas of the breast, prostate, colon, and stomach compared with normal tissue samples. The observation that DARPP-32 and t-DARPP are frequently over-expressed in common subtypes of human cancers suggests that these proteins may play a role in tumorigenesis. The expression of t-DARPP has been shown to increase the AKT kinase activity and regulate the levels of BCL2 in cancer cells. This effect is believed to mediate resistance to drug-induced apoptosis.

Cytosolic

Unknown

Unknown