Differences in myofilament calcium sensitivity in rat psoas fibers reconstituted with troponin T isoforms containing the alpha- and beta-exons |
| |
Authors: | Gallon Clare E Tschirgi Matthew L Chandra Murali |
| |
Affiliation: | Department of Veterinary Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA 99164-6520, USA. |
| |
Abstract: | The carboxy terminus of fast skeletal muscle troponin T (fsTnT) is highly conserved. However, mutually exclusive splicing of exons 16 and 17 in the fsTnT gene results in the expression of either the alpha- or beta-fsTnT isoform. The alpha-isoform is expressed only in adult fast skeletal muscle, whereas the beta-isoform is expressed in varying quantities throughout muscle development. Reconstitution of detergent-skinned adult rat psoas muscle fibers with rat fast skeletal troponin complexes containing either fsTnT isoform demonstrated that reconstitution with alpha-fsTnT resulted in greater myofilament Ca(2+) sensitivity than reconstitution with beta-fsTnT, without changes to Ca(2+)-activated maximal tension, ATPase activity or tension cost. The observed isoform-specific differences in myofilament Ca(2+) sensitivity may be due to changes in the transition of the thin-filament regulatory unit from the off to the on state, possibly due to altered interactions of the C-terminus of fsTnT with troponins I and/or C. |
| |
Keywords: | Fast skeletal muscle Troponin T ATPase activity Tension Skinned muscle fibers Isoforms Rat Tension cost Thin filament Ca2+ sensitivity |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|