Troponin Structure and Function in Health and Disease

Article Figures & Data

Download figure
Open in new tab
Download powerpoint
Figure 1.
Sarcomere organization. A sarcomere is the smallest functional unit of muscle contraction. It is organized from Z disc to Z disc (termed the A Band), with an M line found in the center. The functional unit consists of the actin and myosin filaments, which will slide over one another toward the M line during contraction and shrink the H zone. Image reprinted with permission of John Nagy.
Download figure
Open in new tab
Download powerpoint
Figure 2.
Power stroke image of muscle contraction. (A) Resting with myosin-binding sites covered, (B) calcium binding to troponin, myosin-binding sites exposed, (C) Cross-bridge formation as myosin binds to the myosin-binding sites on actin, (D) Power stroke which moves actin toward the M line, and (E) Dissociation of myosin head from actin. Image reprinted with permission of John Nagy.

Table 1.

Troponin isoforms and chromosomal location

TnI
Gene	Protein Isoform	Chromosome	Expression Site
TNNI1	ssTnI	1q32	Slow twitch skeletal muscle
TNNI2	fsTnI	11p15.5	Fast twitch skeletal muscle
TNNI3	cTnI	19q13.4	Cardiac muscle
TnT
Gene	Protein Isoform	Chromosome	Expression Site
TNNT1	ssTnT	19q13.4	Slow twitch skeletal muscle
TNNT2	cTnT	1q32	Cardiac muscle
TNNT3	fsTnT	11p15.5	Fast twitch skeletal muscle
TnC
Gene	Protein Isoform	Chromosome	Expression Site
TNNC1	cTnC	3p14.3-p21.3	Cardiac or slow skeletal muscle
TNNC2	fsTnC	20q12-q13.11	Fast twitch skeletal muscle

Adapted from Barton et al 1997⁴⁸

Table 2.

Key biology terms used in this article

Keyword	Definition
Central dogma	The 2-step process of transcription and translation, which takes genetic material in the form of DNA (nucleic acids) and converts it to the final protein product.
Transcription	The process of converting the DNA into RNA.
Translation	The process converting RNA into a protein.
Alternative splicing	During transcription, a single gene that codes for multiple proteins by coding for differing exons. These differences can cause changes to protein structure and function.
Posttranscriptional modification	A modification, such as phosphorylation, to a protein after it has been completely translated. This can cause changes to protein function and activity.