Chicken leg muscle alpha-connectin as studied by a monoclonal antibody to the 1200 kDa fragment

Chicken leg gracilis muscle contained only alpha-connectin (ca 3000 kDa) without beta-connectin. When myofibrils were kept standing for 20 hr at 4 degrees C, alpha-connectin was degraded to beta-connectin (ca 2000 kDa) and 1200 kDa peptide. The latter was prepared from myofibrils and purified by gel filtration in the presence of SDS. A monoclonal antibody, alpha 7, to this 1200 kDa fragment was prepared. The antibody reacted with the 1200 kDa fragment and its mother molecule alpha-connectin, but not with beta-connectin. Immunoelectron microscopy using alpha 7, as well as other antibodies to chicken breast muscle beta-connectin, revealed that the 1200 kDa peptide covered the portion of alpha-connectin from the Z line to the N2 line region in the I band of chicken leg gracilis muscle sarcomeres. The results were in good agreement with those observed in rabbit skeletal muscle.