RMDN3

Regulator of microtubule dynamics protein 3 (RMDN3), more commonly known as Protein tyrosine phosphatase interacting protein 51 (PTPIP51), is a is_associated_with::protein that in humans is encoded by the RMDN3 is_associated_with::gene on chromosome 15. This protein contributes to multiple biological functions, including cellular differentiation, proliferation, motility, cytoskeleton formation, and apoptosis, and has been associated with numerous cancers.

Structure
PTPIP51 contains two conserved domains, called conserved region 1 (CR1) and conserved region 2 (CR2), which serve as binding sites for 14-3-3 proteins. Close to these conserved domains are two tyrosine residues, tyrosine 53 and 158, which serve as phosphorylation sites for various kinases. In addition, PTPIP51 has a mitochondrial targeting sequence at its N-terminal which is responsible for inducing apoptosis, though some splicing variants lack this sequence.

Function
PTPIP51 is involved in cellular differentiation, proliferation, motility, cytoskeleton formation, and apoptosis. These biological functions thus serve to facilitate mammalian development through processes such as placental villi formation and angiogenesis. In particular, it is expressed in differentiated cells and tissues, such as follicular and inter-follicular epidermis, epithelia, skeletal muscle, testis, and nervous tissue. PTPIP51 is also expressed differentially in neutrophils, but not other immune cells, and thus may partake in immune cell signaling and myeloid development by interacting with TCPTP and PTP1B. Its interactions with PTP1B, along with the proteins 14-3-3β, Raf-1, c-Src, PKA, and DAGKα, determine the mechanisms by which it influences the mitogen-activated protein kinase (MAPK) pathway.

Clinical Significance
Both the protein and mRNA of PTPIP51 have been implicated in various carcinomas, including prostate carcinoma (PCa), keratinocyte carcinoma, basal cell carcinomas, and squamous cell carcinomas. It is hypothesized that overexpression of PTPIP51 in PCa results from retrotransposon elements activated by CpG island hypomethylation, which has been observed in late prostate carcinogenesis. Moreover, the protein has been observed to interact with is_associated_with::PTP1B to influence the MAPK pathway in acute myeloid leukemia. In addition to cancers, PTPIP51 has been associated with benign prostate hyperplasia (BPH) and, by extension, with BPH-related conditions, including aging and lower urinary tract dysfunction.

Interactions
RMDN3 has been shown to interact with:
 * is_associated_with::PTP1B,
 * is_associated_with::TCPTP,
 * is_associated_with::c-Src,
 * is_associated_with::14-3-3β,
 * is_associated_with::14-3-3γ,
 * is_associated_with::Raf-1,
 * PKA,
 * is_associated_with::DAGKα.