Amino acid sequence of the calcium-binding light chain of myosin from the lower eukaryote, Physarum polycephalum.
We have established a new method for preparing Physarum myosin whose actin-activated ATPase activity is inhibited by micromolar levels of Ca2+. This Ca2+-inhibition is mediated by the Ca2+ binding to the myosin rather than by the Ca2+-dependent modification of the phosphorylated state of the myosin (Kohama, K., and Kendrick-Jones, J. (1986) J. Biochem. (Tokyo) 99, 1433-1446). Ca2+-binding light chain (CaLC) has been suggested to be primary importance in this Ca2+ inhibition (Kohama, K., Takano-Ohmuro, H., Tanaka, T., Yamaguchi, T., and Kohama, T. (1986) J. Biol. Chem. 261, 8022-8027). The amino acid sequence of CaLC was determined; it was composed of 147 amino acid residues and the N terminus was acetylated. The molecular weight was calculated to be 16,131. The homology of CaLC in the amino acid sequence with 5,5'-dithiobis-(2-nitrobenzoic acid) light chain and alkali light chain of skeletal muscle myosin were rather low, i.e., 25% and 30%, respectively. Interestingly, however, the CaLC sequence was 40% homologous with brain calmodulin. This amino acid sequence was confirmed by sequencing the cloned phage DNA accommodating cDNA coding CaLC. Northern and Southern blot analysis indicated that 0.8-kilobase pair mRNA was transcribed from a single CaLC gene. This is the first report on the amino acid sequence of myosin light chain of lower eukaryotes and nucleotide sequence of its mRNA.
Kobayashi
T
T
Biological Institute, Faculty of Science, Tohoku University, Sendai, Japan.
Takagi
T
T
Konishi
K
K
Hamada
Y
Y
Kawaguchi
M
M
Kohama
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D008969:Molecular Sequence Data; D015879:Myosin Subfragments; D009218:Myosins / Q000235:genetics* / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics* / Q000378:metabolism; D010804:Physarum / Q000378:metabolism*; D011487:Protein Conformation
D015879:Myosin Subfragments; D010446:Peptide Fragments; D004247:DNA; D009218:Myosins; D002118:Calcium