Identification of functioning regulatory sites and a new myosin binding site in the C-terminal 288 amino acids of caldesmon expressed from a human clone
✍ Scribed by P. A. J. Huber; C. S. Redwood; N. D. Avent; M. J. A. Tanner; S. B. Marston
- Publisher
- Springer Netherlands
- Year
- 1993
- Tongue
- English
- Weight
- 861 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0142-4319
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✦ Synopsis
A partial clone of caldesmon, coding for the C-terminal 288 amino acids, was isolated from a human fetal liver cDNA library and sequenced. Expression of the clone in Escherichia coli produced a peptide called H1 (M r 32 549), which inhibited tropomyosin-enhanced actomyosin Mg2+-ATPase activity by 90% with half maximal inhibition at 0.03--0.04 mol H1 per mol actin. The inhibition could be reversed by Ca2+-calmodulin. H1 bound actin, Ca2+-calmodulin and tropomyosin and smooth muscle myosin with high affinities. This latter finding shows the presence of a second myosin-binding site in caldesmon. This was confirmed in thrombic digests of native sheep aorta and chicken gizzard caldesmon.