Molluscan smooth catch muscle contains calponin but not caldesmon.
We isolated Ca(2+)-regulated thin filaments from the smooth muscle of the mussel Crenomytilus grayanus and studied the protein composition of different preparations from this muscle: whole muscle, heat-stable extract, fractions from heat-stable extract, thin filaments and intermediate stages of thin filaments purification. Among the protein components of the above-listed preparations, we did not find caldesmon (CaD), although two isoforms of a calponin-like (CaP-like) protein, which along with CaD is characteristic of vertebrate smooth muscle, were present in thin filaments. Thus, CaD is not Ca(2+)-regulator of thin filaments of this muscle. On the other hand, the mussel CaP-like protein is also not such Ca(2+)-regulator since we have shown that this protein can be selectively removed from isolated mussel thin filaments without loss of their Ca(2+)-sensitivity. We suggest that thin filaments in the smooth catch muscle possess other type of Ca(2+)-regulation, different from that in vertebrate smooth muscles.
Laboratory of Cell Biophysics, A.V. Zhirmunsky Institute of Marine Biology, Far East Branch of the Russian Academy of Sciences, Vladivostok, Russia.
Anna V
AV
Dobrzhanskaya
Ilya G
IG
Vyatchin
Stanislav S
SS
Lazarev
Oleg S
OS
Matusovsky
Nikolay S
NS
Shelud'ko
D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D015153:Blotting, Western; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D005591:Chemical Fractionation / Q000379:methods; D002645:Chickens / Q000378:metabolism / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D057075:Enzyme Assays; D005895:Gizzard, Avian / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism* / Q000502:physiology; D025941:Protein Interaction Mapping; D055550:Protein Stability; D011817:Rabbits; D013045:Species Specificity; D013696:Temperature; D014335:Tropomyosin / Q000378:metabolism; D000096985:Calponins
D000199:Actins; D000205:Actomyosin; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium; D002135:Calcium-Binding Proteins; D002148:Calmodulin-Binding Proteins; D008840:Microfilament Proteins; D014335:Tropomyosin; D000096985:Calponins