Absence of Nebulin in Cardiac Muscles of the Chicken Embryo

Nebulin, a high molecular weight (~700 kDa) protein of vertebrate skeletal muscle, was not detected in embryonic and adult cardiac muscles of the chicken by SDS-gel electrophoresis. No peptides reactive with anti-nebulin antiserum were found by immunoblot tests. Nebulin was detected in chicken embryonic skeletal muscles after 17 days of incubation. On the other hand, connectin, another giant protein, was present in both cardiac and skeletal muscles of the chicken embryos after 15 days of incubation.