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The Positively Charged C-Terminal Region of Human Skeletal Troponin T Retards Activation and Decreases Calcium Sensitivity
- Source :
- Biochemistry. 59:4189-4201
- Publication Year :
- 2020
- Publisher :
- American Chemical Society (ACS), 2020.
-
Abstract
- Calcium binding to troponin C (TnC) activates striated muscle contraction by removing TnI (troponin I) from its inhibitory site on actin. Troponin T (TnT) links TnI with tropomyosin, causing tropomyosin to move from an inhibitory position on actin to an activating position. Positive charges within the C-terminal region of human cardiac TnT limit Ca2+ activation. We now show that the positively charged region of TnT has an even larger impact on skeletal muscle regulation. We prepared one variant of human skeletal TnT that had the C-terminal 16 residues truncated (Δ16) and another with an added C-terminal Cys residue and Ala substituted for the last 6 basic residues (251C-HAHA). Both mutants reduced (based on S1 binding kinetics) or eliminated (based on acrylodan-tropomyosin fluorescence) the first inactive state of actin at
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 59
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....469a88fb625869aed804a29318722193