|Detection of Human, Mouse, and Rat PALS1/MPP5 by Western Blot. Western blot shows lysates of HeLa human cervical epithelial carcinoma cell line, MCF‑7 human breast cancer cell line, bEnd.3 mouse endothelioma cell line, and Rat‑2 rat embryonic fibroblast cell line. PVDF membrane was probed with 0.5 µg/mL of Sheep Anti-Human/Mouse/Rat PALS1/MPP5 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF7979) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). Specific bands were detected for PALS1/MPP5 at approximately 75-80 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
MPP5 (Membrane Palmitoylated Protein 5; also PALS1/Proteins Associated with Lin7 #1) is a 70-80 kDa member of MAGUK (Membrane-Associated Guanylate Kinase) family of proteins. It is ubiquitously expressed, and plays a key role in the creation of cell polarity and adhesion. Although not its only function, MPP5 is essential for tight junction integrity. Crumbs proteins (Crb-1 and -3) are apically-oriented, integral membrane proteins. These transmembrane proteins are known to bind to cytosolic MPP5, which, in turn, links to PATJ, which, in turn, binds to either cytosolic ZO-3, or to 4-transmembrane laterally-embedded claudin-1. Subsequent binding of ZO-3 with actin unite the cytoskeleton with the cell membrane. Human MPP5 is 675 amino acids (aa) in length. It contains a utilized phosphorylation site at Ser25, two consecutive L27 domains (aa 120-177 and 179-235) that bind PATJ, one PDZ domain (aa 256-336) that binds crumb proteins, an SH3 region (aa 345-417), and a C‑terminal guanylate kinase-like domain (aa 479-660). MPP5 forms both homodimers and heterodimers with MPP4. There is one splice variant that utilizes an alternative start site at Met35. Over aa 392-509, human and mouse MPP5 are identical in amino acid sequence. Overall, human and mouse MPP5 share 97% aa sequence identity.