The cardiac gap junction protein (Mr 47,000) has a tissue-specific cytoplasmic domain of Mr 17,000 at its carboxy-terminus.
The molecular weight of the heart gap junctional protein subunit was, until recently, believed to be about Mr 28,000-30,000, similar to that of other previously characterized gap junctional proteins. A larger polypeptide of about Mr 44,000-47,000, which undergoes proteolysis during isolation, has recently been proposed as the form of the heart junction protein in vivo. We show here that this entity has the same amino-terminal sequence as the previously characterized Mr 29,000-30,000 component. Thus, the cardiac junctional protein has, at its carboxy-terminus, cytoplasmic domain of Mr 17,000; this domain is absent in the liver protein. These observations provide further evidence that gap junction proteins form a highly diversified family.
D000595:Amino Acid Sequence; D017630:Connexins; D003593:Cytoplasm; D007365:Intercellular Junctions / Q000032:analysis*; D008099:Liver / Q000032:analysis; D008565:Membrane Proteins / Q000302:isolation & purification*; D008970:Molecular Weight; D009206:Myocardium / Q000032:analysis*; D010447:Peptide Hydrolases / Q000378:metabolism; D011487:Protein Conformation
D017630:Connexins; D008565:Membrane Proteins; D010447:Peptide Hydrolases