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troponin-C
Function:
- Ca+2-sensing component of troponin complex
- in resting muscle, high affinity Ca+2-binding sites in the C-terminal region (Kd = 0.1 uM) are occupied, but the low affinity ones in the N-terminal regions (Kd = 10 uM) are not
- when Ca+2 is released from the sarcoplasmic reticulum, it occupies the low affinity sites & induces a conformational change that is transmitted though troponin-I & troponin-T to tropomyosin
- Ca+2 controls muscle contraction by an allosteric mechanism in which the flow of information is: Ca+2 -> troponin -> tropomyosin -> actin -> myosin
Structure:
- troponin C closely resembles calmodulin
Specific
troponin C, skeletal muscle (TNNC2)
troponin C, slow skeletal & cardiac muscles; TN-C (TNNC1 TNNC)
General
Ca+2 binding protein
protein subunit
Properties
SIZE: MW = 18 kD
MOTIF: acetylation site
SITE: N-TERMINUS
EFFECTOR-BOUND: acetyl
Ca+2-binding site (2)
SITE: N-TERMINAL
Ca+2-binding site (2)
SITE: C-TERMINAL
EFFECTOR-BOUND: Ca+2
References
- Textbook of Biochemistry with Clinical Correlations,
3rd ed., TM Devlin (ed), Wiley-Liss, NY 1992 pg 961
- Stryer Biochemistry WH Freeman & Co, New York,
1988 pg 933
Component-of
troponin