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J Membr Biol. 1996 Feb;149(3):199-209.

Identification of isoforms of G proteins and PKC that colocalize with tight junctions.

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Laboratory of Cellular Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA.


Recent evidence suggests that the formation and permeability of tight junctions are actively regulated by second-messenger-generating systems involving G proteins and protein kinase C (PKC). A possible specific target for these regulatory proteins is the tight junction protein ZO-1. An extensive immunocytochemical study was performed in cultured epithelial monolayers of MDCK and Caco-2 cells to identify which isoforms of G proteins and PKC are present at or near zonula occludens complex. Antibodies against alpha-subunits of each one of the four major subfamilies were used for the localization of the G proteins. For the PKC localization, antibodies against eight different isoforms were used. In confluent monolayers, G alpha 12 and PKC zeta, were the only isoforms of these proteins at the cell borders. In subconfluent monolayers, G alpha 12 and PKC zeta were found at the plasma membrane only along the areas of lateral cell-cell contact. These isoforms formed a pattern of distribution very similar to the ZO-1 protein. The present findings indicate that G alpha 12 and PKC zeta may be part of the zonula occludens complex and may locally regulate formation and permeability of tight junctions.

[Indexed for MEDLINE]

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