Mg. Price et Rh. Gomer, SKELEMIN, A CYTOSKELETAL M-DISC PERIPHERY PROTEIN, CONTAINS MOTIFS OFADHESION RECOGNITION AND INTERMEDIATE FILAMENT PROTEINS, The Journal of biological chemistry, 268(29), 1993, pp. 21800-21810
In striated muscle, myofibrils are anchored to an interconnecting cyto
skeleton of desmin intermediate filaments. Skelemin (195 kDa) may be a
link between myofibrils and the intermediate filament cytoskeleton. S
kelemin partitions with desmin to the insoluble cytoskeleton, and incr
eases the thickness of reconstituted intermediate filaments. Concentra
ted at the M-disc periphery, skelemin may also contact myosin filament
s. We used immunoscreening to isolate a mouse muscle cDNA which encode
s a protein with a calculated molecular mass of 185 kDa. Anti-skelemin
antibodies bound to the protein products of each of three nonoverlapp
ing regions of the open reading frame. Antibodies directed against the
protein products of each one-third of the cDNA react with a 195-kDa m
uscle protein and stain the M-disc indistinguishably from the original
anti-skelemin antibodies, suggesting that the cDNA encodes skelemin.
A single skelemin mRNA is detected in muscle but not non-muscle tissue
s, consistent with immunostaining results. Skelemin is a member of a f
amily of myosin-associated proteins containing fibronectin type III an
d immunoglobulin superfamily C2 motifs. Skelemin is unique in this fam
ily in having intermediate filament core-like motifs, one near each te
rminus. We hypothesize that skelemin could interact with myosin or myo
sin-associated proteins through its fibronectin and/or immunoglobulin
motifs, and with intermediate filaments through intermediate filament-
like motifs.