Distribution of the Ca2+-binding S100A1 protein at different sarcomere lengths of slow and fast rat skeletal muscles.
The localization of S100A1 in rat soleus (SOL) and extensor digitorum longus (EDL) muscles was studied immunocytochemically at different sarcomere lengths (stretched, relaxed and contracted) at the ultrastructural level. The muscle fibres were contracted by application of 15 mmol/l caffeine. Following aldehyde fixation, dehydration and embedding in Lowicryl HM20 (-35 degrees C) ultrathin sections were incubated with rabbit polyclonal antiserum against S100A1. Goat antirabbit secondary antibodies conjugated with 10 nm gold particles were used to visualize antigen sites. Relative areas of Z-lines, A- and I-bands were estimated from longitudinal sections by the point counting method. The highest densities of the particles were found at the Z-lines. A higher incidence of S100A1 antigen sites in I-bands than in A-bands and a higher density of S100A1 in lateral parts of A-bands (with actin and myosin filaments overlapping) compared with the central area of A-bands are consistent with an interaction of S100A1 with F-actin in skeletal muscles. Antigen sites were also present at M-lines and at distinct locations of the sarcoplasmic reticulum.
Maco
B
B
Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava.
Uhrík
B
B
Heizmann
C W
CW
D000199:Actins / Q000378:metabolism; D000818:Animals; D000941:Antigens / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D007150:Immunohistochemistry; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism* / Q000648:ultrastructure; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism* / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000648:ultrastructure; D009218:Myosins / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D009418:S100 Proteins; D012518:Sarcomeres / Q000378:metabolism*
D000199:Actins; D000941:Antigens; D002135:Calcium-Binding Proteins; D009418:S100 Proteins; C110294:S100A1 protein; D002110:Caffeine; D009218:Myosins; D002118:Calcium