| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Calmodulin is thought to be a physiological regulator of the Ca^<2+> release channel (ryanodine receptor, RyR) in the sarcoplasmic reticulum (SR) of striated muscles. In the process of looking for a new calmodulin-binding protein in the SR fraction from the rabbit psoas muscle, I have noted a 55 kd calmodulin-binding protein (55K protein). The character of 55 K protein analyzed is as follows.
1) 55 K protein presents in a partial purified Rya R fraction.
2) Judging from the results of a partial amino acid sequence, its molecular weight, and its antigenicities, 55 K protein appears to resemble one of the diaphorases, lipoamidodehydrogenase. The protein seems to be identical to the enzyme, but calmodulin binding of the enzyme has not yet been demonstrated.
3) 55 K protein consisits of proteins having different isoelectric points. These proteins are probably the products of post-translational modification, such as phosphorylation. ^<125>I-calmodulin binds to all the proteins.
4) 55 K protein was expressed in only skeletal muscle, not in aorta, heart, brain, or liver.
5) 55 K protein was found to be present near the A-I junction of the sarcomere.
6) In an immunoprecipitation experiment with using the antibody, it was revealed that 55 K protein could interact with Rya R in a direct or in an indirect manner.
These result strongly suggest that 55 K protein is one of candidates which have some functions on the signal transduction from DHP receptor at T-tuble to RyR in the sarcoplasmic reticulum during excitation-contraction coupling in skeletal muscle.
cDNA cloning of 55 K protein is in progress.
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