In situ compartmentation of creatine kinase in intact sarcomeric muscle: the acto-myosin overlap zone as a molecular sieve.

摘要: Creatine kinase isoenzymes (CK = ATP: creatine N-phosphoryl transferase, EC 2.7.3.2) were localized in situ cryosections of intact sarcomeric muscle by immunocytochemical staining. Similar to cardiac muscle, spermatozoa and photoreceptor cells, mitochondrial-type CK (Mi-CK) localization skeletal was also restricted mitochondria. Besides the well-documented muscle-type (M-CK) at M-line sarcoplasmic reticulum, surprisingly, most M-CK highly compartmentalized mainly confined I-band. The I-band coincided with that adenylate aldolase. In diffusion equilibrium decisively favours occupancy all three enzymes I-band, acto-myosin overlap region A-band acting as a molecular sieve, excluding large extent from region. This indicates this may be less accessible vivo soluble, than thought before. If permeabilized chemical skinning before fixation, CK, well aldolase kinase, solubilized disappeared myofibrils, but fraction which specifically associated remained bound myofibrils. Implications these findings are discussed respect functional coupling I-band-CK glycolysis, formation multienzyme complexes glycolytic supply energy for contraction general.