ARFIP1 Human

ADP-Ribosylation Factor Interacting Protein 1 (ARFIP1), also known as Arfaptin-1, is a protein encoded by the ARFIP1 gene in humans. This protein plays a crucial role in intracellular protein transport and regulation of protein secretion. It is involved in the biogenesis of secretory granules at the trans-Golgi network and is essential for proper secretory granule formation in pancreatic beta cells .

ARFIP1 contains a single AH (amphipathic helix) domain and is a target protein of ADP-ribosylation factor (ARF). The protein is a non-glycosylated polypeptide chain consisting of 396 amino acids, with a molecular mass of approximately 44.1 kDa . ARFIP1 binds to ARF-GTP at the neck of a growing secretory granule precursor, forming a protective scaffold. Once the granule precursor is fully loaded, ARFIP1 is phosphorylated by PRKD1, leading to its release from ARFs, which then induce fission .

ARFIP1 is involved in several critical cellular processes:

• Intracellular Protein Transport: ARFIP1 plays a role in the negative regulation of retrograde transport from endosomes to the Golgi apparatus .
• Secretory Granule Formation: It ensures the proper formation of secretory granules at the Golgi, particularly in pancreatic beta cells .
• Phosphatidylinositol-4-Phosphate Binding: ARFIP1 has binding activity specific to phosphatidylinositol-4-phosphate, which is crucial for its function in intracellular transport .

The ARFIP1 gene is located on chromosome 4 and has several aliases, including Arfaptin-1 and ADP-Ribosylation Factor-Interacting Protein 1 . It is a protein-coding gene with important paralogs such as ARFIP2. The gene is highly conserved across different species, indicating its essential role in cellular functions .

The human recombinant ARFIP1 is produced in Escherichia coli (E. coli) as a single, non-glycosylated polypeptide chain. This recombinant protein is used in various research applications to study its function and role in cellular processes .