Tight-junction protein zonula occludens 2 is a target of phosphorylation by protein kinase C.
Zonula occludens 2 (ZO-2) protein is a tight-junction phos phorylated protein that belongs to the membrane-associated guanylate kinase ('MAGUK') family. Here we study the interaction between ZO-2 and protein kinase C (PKC). We have constructed two ZO-2 fusion proteins of the middle (3PSG) and C-terminal (AP) regions of the molecule and demonstrate that they are phosphorylated by PKC isoenzymes beta, epsilon, lambda and zeta. To understand the physiological significance of the interaction between ZO-2 and PKC, we analysed the phosphorylation state of ZO-2 immunoprecipitated from monolayers with mature tight junctions or from cells that either lack them or have them disassembled through Ca(2+) chelation. We found that in the latter condition the phosphorylation level of ZO-2 is significantly higher and is due to the action of both PKC and cAMP-dependent protein kinase. These results therefore suggest that the phosphorylated state of ZO-2 restrains its capacity to operate at the junctional complex.
Avila-Flores
A
A
Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), A. Postal 14-740, México D.F. 07000.
Rendón-Huerta
E
E
Moreno
J
J
Islas
S
S
Betanzos
A
A
Robles-Flores
M
M
González-Mariscal
L
L
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004285:Dogs; D005982:Glutathione Transferase / Q000235:genetics; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D051744:Protein Kinase C-epsilon; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D019108:Tight Junctions / Q000201:enzymology / Q000378:metabolism*; D062827:Zonula Occludens-2 Protein; D000099293:Protein Kinase C-lambda; D000099221:Protein Kinase C zeta
D002118:Calcium; D017868:Cyclic AMP-Dependent Protein Kinases; D005982:Glutathione Transferase; D007527:Isoenzymes; D008565:Membrane Proteins; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051744:Protein Kinase C-epsilon; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins; D012694:Serine; D013912:Threonine; D062827:Zonula Occludens-2 Protein; D000099293:Protein Kinase C-lambda; D000099221:Protein Kinase C zeta; C497257:Prkce protein, rat