PIP Human

The PIP gene is located on chromosome 7 (7q34) in humans . It is expressed in various tissues, including the apocrine glands in the axilla, vulva, eyelid, and ear canal, as well as the serous cells of the submandibular salivary gland, submucosal glands of the bronchi, and accessory lacrimal glands . Additionally, PIP is found in amniotic fluid and seminal fluid .

PIP plays a significant role in the regulation of water transport in the aforementioned glands . It has the ability to bind to immunoglobulin G (IgG), IgG-Fc, and CD4-T cell receptors, suggesting a wide range of immunological functions . PIP also binds to AZGP1 and exhibits aspartyl proteinase activity, which allows it to cleave fibronectin .

PIP is involved in various immunological processes, including the negative regulation of T cell apoptotic processes and the regulation of immune system processes . It can bind to different species of bacteria, showing the highest affinity to streptococci, thus playing a role in the non-immune defense of the body against pathogenic bacterial strains .

PIP has been observed to have a mitogenic effect on both normal and malignant breast epithelial cells . This protein is also associated with certain diseases, such as breast cysts and perivascular epithelioid cell tumors . Its expression and function in various exocrine tissues, such as the lacrimal, salivary, and sweat glands, highlight its versatile nature and importance in human reproductive and immunological systems .