PAR3beta, a novel homologue of the cell polarity protein PAR3, localizes to tight junctions.
The cell polarity protein PAR3, conserved from the nematode to the vertebrate, forms a complex with PAR6 and atypical protein kinase C (aPKC), and the protein complex occurs at the tight junctions in mammalian epithelial cells. Here we have cloned human cDNA for a novel PAR3 homologue, designated PAR3beta, whose messages are present in a variety of tissues and most abundantly expressed in the adult and fetal kidneys. The encoded protein of 1,205 amino acids contains a region homologous to the aPKC-binding domain of PAR3alpha, another human homologue previously identified, and three PDZ domains; the first PDZ domain of PAR3alpha is considered to interact with PAR6. Unexpectedly, in contrast to other PAR3s found in various species, PAR3beta is incapable of binding to any isotypes of PAR6 or aPKC. Nevertheless PAR3beta, expressed intrinsically or extrinsically, localizes to the tight junctions, indicating that the localization does not require the ternary complex formation.
Kohjima
Motoyuki
M
Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Noda
Yukiko
Y
Takeya
Ryu
R
Saito
Naoaki
N
Takeuchi
Kosei
K
Sumimoto
Hideki
H
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins; D002460:Cell Line; D016764:Cell Polarity; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D018179:Receptors, Thrombin / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D019108:Tight Junctions / Q000737:chemistry / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
D002352:Carrier Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins; C471157:PARD3B protein, human; D010750:Phosphoproteins; D020033:Protein Isoforms; D018179:Receptors, Thrombin; D011993:Recombinant Fusion Proteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C105295:protease-activated receptor 3