Isolation of mouse myocardial gap junctions

A new method is presented for the isolation of an enriched fraction of mouse myocardial gap junctions without the use of exogenous proteases. The junctions appear well preserved morphologically and similar to their appearance in situ. Contaminants of the preparation include fragments of the fascia adherens region of the intercalated disk. SDS polyacrylamide gel electrophoresis of the preparation reveals seven major bands with apparent mol wt of 28,000; 31,000; 33,500; 43,000; 47,000; 49,000; and 57,000. Only the bands at 38,000; 31,000; 33,500; and possibly the diffuse band at 47,000 copurify with the morphologically assayed gap junctions. Evidence is presented that the peptides at 43,000 and 57,000 are contained within the contaminating fascia adherens.