RT Journal Article
SR Electronic
T1 Troponin Structure and Function in Health and Disease
JF American Society for Clinical Laboratory Science
JO Clin Lab Sci
FD American Society of Chemistry and Laboratory Science
SP 192
OP 199
DO 10.29074/ascls.2018000679
VO 31
IS 4
A1 Giordano, Samantha
A1 Estes, Robert
A1 Li, Wei
A1 George, Remo
A1 Gilford, Tosi
A1 Glasgow, Krystle
A1 Hallman, Heather
A1 Josephat, Floyd
A1 Oliveira, Ana
A1 Xavier, Neena
A1 Chiasera, Janelle M.
YR 2018
UL http://hwmaint.clsjournal.ascls.org/content/31/4/192.abstract
AB Troponin (Tn) is a heterotrimeric protein containing 3 subunits (C, T, and I) with different molecular weights and distinctive functions. The subunits of Tn work cohesively to regulate the contraction and relaxation activities of striated muscles: troponin-C (TnC) binds calcium (Ca2+); troponin-T (TnT) interacts with tropomyosin (Tm) and anchors Tn to actin; and troponin-I (TnI) inhibits the adenosine triphosphatase (ATPase) activity of the actomyosin cross-bridge and effectively blocks the myosin-binding site on actin subunits. At a genetic level, there are 8 distinctive Tn genes (isoforms) that code for tissue-specific heart and skeletal muscle protein subunits: TNNI1, TNNI2, TNNI3, TNNT1, TNNT2, TNNT3, TNNC1, and TNNC2. The gene isoforms are regulated throughout development via posttranscriptional and posttranslational modifications. Genetic mutations in any of the 3 protein subunits could be linked to hypertrophic, dilated, and restrictive cardiomyopathies. Tn release by damaged cardiomyocytes is clinically used as a biomarker for myocardial infarction (MI), and its release into the serum is measured at specific times postinjury for diagnostic or prognostic purposes. Current tests that measure serum Tn are fifth generation assays, which have improved sensitivity and specificity compared with previous assays. However, increased serum Tn levels have been seen in chronic diseases such as Fabry disease and chronic renal disease. It is important to remember, when clinically examining a patient, that Tn levels are only one piece of the puzzle. A patient’s history or symptoms are essential for making an accurate diagnosis.