GIPC1

GIPC1 (GAIP-interacting protein, C‑terminus homolog 1) is a protein encoded by the GIPC1 gene located on chromosome 3q13.3 in humans. The protein contains a single PDZ domain that mediates interactions with the C‑terminal motifs of target proteins. GIPC1 is expressed ubiquitously, with higher levels in brain, kidney, and testis, and its expression can be modulated during development and in response to cellular stress.

At the cellular level, GIPC1 functions primarily as a scaffold that links membrane receptors to downstream signaling pathways. It binds the G‑protein alpha subunit GAIP (Gαi-binding protein) and many type‑I transmembrane receptors, including the insulin receptor, G protein–coupled receptors, and some adhesion molecules. Through these interactions it influences receptor trafficking, endocytosis, and signal transduction. GIPC1 also associates with the small GTPase Rab8 and the kinesin motor protein KIF13A, thereby contributing to the regulation of vesicular transport from the Golgi apparatus to the plasma membrane.

Altered GIPC1 expression has been reported in several human cancers. Overexpression is observed in colorectal, breast, and pancreatic tumors and is correlated with increased proliferation, migration, and invasion of cancer cells. These phenotypes are thought to arise from aberrant receptor trafficking and dysregulated signal cascades mediated by GIPC1. In addition, genetic variations in the GIPC1 locus have been linked to susceptibility for autoimmune disorders such as rheumatoid arthritis.

Ongoing research aims to clarify the precise molecular mechanisms by which GIPC1 coordinates membrane receptor dynamics and to evaluate its potential as a therapeutic target in oncology and metabolic disease.