tyrosine protein kinase 7; colon carcinoma kinase 4; CCK-4; protein tyrosine kinase 7; pseudo tyrosine kinase receptor 7; tyrosine protein kinase-like 7 (PTK7, CCK4)
Jump to navigation
Jump to search
Function
- inactive tyrosine kinase involved in Wnt signaling pathway
- component of both the non-canonical (also known as the Wnt/planar cell polarity signaling) & the canonical Wnt signaling pathway
- functions in cell adhesion, cell migration, cell polarity, proliferation, actin cytoskeleton reorganization & apoptosis
- role in embryogenesis, epithelial tissue organization & angiogenesis
- MMP14 cleaves PTK7 between Pro-621 & Leu-622 generating an N-terminal soluble (70 kDa) fragment & a membrane C-terminal (50 kDa) fragment
- proteolysis by MMP14 regulates PTK7 function in the non-canonical Wnt signaling pathway
- interacts with CTNNB1
Structure
- belongs to the protein kinase superfamily, Tyr protein kinase family, insulin receptor subfamily
- contains 7 Ig-like C2-type domains
- contains 1 protein kinase domain
Compartment
- membrane
- single-pass type 1 membrane protein
- cell junction
- colocalizes with MMP14 at cell junctions
- also localizes at the leading edge of migrating cells
Alternative splicing
- named isoforms=5
- at least 1 isoform may be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay
Expression
- highly expressed in lung, liver, pancreas, kidney, placenta & melanocytes
- weakly expressed in thyroid gland, ovary, brain, heart & skeletal muscle
- also expressed in erythroleukemia cells
- not expressed in colon
- higher expression in cell lines established from normal non-tumorigenic tissues compared to cell lines established from highly metastatic invasive carcinomas (at protein level)