Pituitary Tumor Transforming 1 Interacting Protein (PTTG1IP)

PTTG1IP, which directly binds to pituitary tumor-transforming gene 1 protein (PTTG1), facilitates the nuclear translocation of PTTG1 and potentiates the transcriptional activation of basic fibroblast growth factor by PTTG1. The gene product localizes to both the cytoplasm and nucleus. Its NLS is required for its own nuclear localization, the nuclear localization of PTTG1, and its interaction with PTTG1.

The predicted 180-amino acid C21ORF3 protein has features of a type Ia integral membrane protein and contains the tetrapeptide YXRF, a motif observed in proteins internalized via coated pit-mediated endocytosis. Northern blot analysis detected a 2.69-kb C21ORF3 mRNA in all tissues examined.