Antisera Directed against Connexin43 Peptides React with a 43-kD Protein Localized to Gap Junctions in Myocardium and Other Tissues

• Published in: The Journal of cell biology Vol. 108; no. 2; pp. 595 - 605
• Main Authors: Beyer, Eric C., Kistler, Joerg, Paul, David L., Goodenough, Daniel A.
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.02.1989; The Rockefeller University Press
• Subjects: Animals; Antibodies; Antiserum; Biological and medical sciences; Blotting, Northern; Blotting, Western; Cell interactions, adhesion; Cells; Connective Tissue - ultrastructure; Connexins; Epithelial cells; Female; Fiber cells; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Gap junctions; Granulosa cells; Granulosa Cells - ultrastructure; Immunohistochemistry; Intercellular Junctions - analysis; Liver; Liver - ultrastructure; Membrane Proteins - analysis; Microscopy, Electron; Molecular and cellular biology; Muscle, Smooth - ultrastructure; myocardium; Myocardium - ultrastructure; Rats; Reactivity; Tissue Distribution; Heart; Immunohistochemistry; Peptides; Rat; Rodentia; Cell junction; Gap junction; Tissue; Vertebrata; Mammalia; Myocardium; Immunoblotting assay; Localization
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.108.2.595

Rat heart and other organs contain mRNA coding for connexin43, a polypeptide homologous to a gap junction protein from liver (connexin32). To provide direct evidence that connexin43 is a cardiac gap junction protein, we raised rabbit antisera directed against synthetic oligopeptides corresponding to two unique regions of its sequence, amino acids 119-142 and 252-271. Both antisera stained the intercalated disc in myocardium by immunofluorescence but did not react with frozen sections of liver. Immunocytochemistry showed anti-connexin43 staining of the cytoplasmic surface of gap junctions in isolated rat heart membranes but no reactivity with isolated liver gap junctions. Both antisera reacted with a 43-kD polypeptide in isolated rat heart membranes but did not react with rat liver gap junctions by Western blot analysis. In contrast, an antiserum to the conserved, possibly extracellular, sequence of amino acids 164-189 in connexin32 reacted with both liver and heart gap junction proteins on Western blots. These findings support a topological model of connexins with unique cytoplasmic domains but conserved transmembrane and extracellular regions. The connexin43-specific antisera were used by Western blots and immunofluorescence to examine the distributon of connexin43. They demonstrated reactivity consistent with gap junctions between ovarian granulosa cells, smooth muscle cells in uterus and other tissues, fibroblasts in cornea and other tissues, lens and corneal epithelial cells, and renal tubular epithelial cells. Staining with the anticonnexin43 antisera was never observed to colocalize with antibodies to other gap junction proteins (connexin32 or MP70) in the same junctional plaques. Because of limitations in the resolution of the immunofluorescence, however, we were not able to determine whether individual cells ever simultaneously express more than one connexin type.