Repetitive titin epitopes with a 42 nm spacing coincide in relative position with known A band striations also identified by major myosin-associated proteins. An immunoelectron-microscopical study on myofibrils.
A direct titin-thick filament interaction in certain regions of the A band is suggested by results using four new monoclonal antibodies specific for titin in immunoelectron microscopy. Antibodies T30, T31 and T32 identify quasi-repeats in the titin molecule characterized by a 42-43 nm repeat spacing. These stripes seem to coincide with striations established by others on negatively stained cryosections of the A band. Antibodies T30 and T32 recognize epitopes matching five or two of the seven striations per half sacromere known to harbor both the myosin-associated C-protein and an 86K (K = 10(3) Mr) protein. Antibody T31 labels two stripes in the P zone, which correspond to the two positions where decoration is seen with 86K protein, but not with C-protein. The single titin epitope defined by antibody T33 is located 55 nm prior to the center of the M band. This position seems to coincide with the M7 striation defined by others on negatively stained A bands. The T33 epitope position proves that the titin molecule, which is known to be anchored at the Z line, also penetrates into the complex architecture of the M band. The titin epitopes described here enable us to begin to correlate known ultrastructural aspects of the interior part of the A band with the disposition of the titin molecule in the sarcomere. They raise the question of whether there is a regular interaction pattern between titin and the thick filaments.(ABSTRACT TRUNCATED AT 250 WORDS)
Fürst
D O
DO
Max Planck Institute for Biophysical Chemistry, Goertingen, FRG.
Nave
R
R
Osborn
M
M
Weber
K
K
D000818:Animals; D000911:Antibodies, Monoclonal; D002645:Chickens; D064211:Connectin; D000939:Epitopes; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure*; D009132:Muscles / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D009210:Myofibrils / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure*; D009218:Myosins / Q000378:metabolism; D011494:Protein Kinases
D000911:Antibodies, Monoclonal; D064211:Connectin; D000939:Epitopes; D009124:Muscle Proteins; D011494:Protein Kinases; D009218:Myosins