title: Comprehensive analysis of tropomyosin isoforms in skeletal muscles by top-down proteomics.
abstract: Mammalian skeletal muscles are heterogeneous in nature and are capable of performing various functions. Tropomyosin (Tpm) is a major component of the thin filament in skeletal muscles and plays an important role in controlling muscle contraction and relaxation. Tpm is known to consist of multiple isoforms resulting from different encoding genes and alternative splicing, along with post-translational modifications. However, a systematic characterization of Tpm isoforms in skeletal muscles is still lacking. Therefore, we employed top-down mass spectrometry (MS) to identify and characterize Tpm isoforms present in different skeletal muscles from multiple species, including swine, rat, and human. Our study revealed that Tpm1.1 and Tpm2.2 are the two major Tpm isoforms in swine and rat skeletal muscles, whereas Tpm1.1, Tpm2.2, and Tpm3.12 are present in human skeletal muscles. Tandem MS was utilized to identify the sequences of the major Tpm isoforms. Furthermore, quantitative analysis revealed muscle-type specific differences in the abundance of un-modified and modified Tpm isoforms in rat and human skeletal muscles. This study represents the first systematic investigation of Tpm isoforms in skeletal muscles, which not only demonstrates the capabilities of top-down MS for the comprehensive characterization of skeletal myofilament proteins but also provides the basis for further studies on these Tpm isoforms in muscle-related diseases.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
authors.forename: Yutong
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.|Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.|Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
authors.forename: Ziqing
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.|Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, P.R. China.
authors.forename: Liming
authors.initials: L
authors.lastname: Wei
authors.affiliation: Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Hacker
authors.affiliation: Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Clinical Neurophysiology Section, Karolinska Institutet, 171 77, Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Larsson
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA. ying.ge@wisc.edu.|Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA. ying.ge@wisc.edu.|Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA. ying.ge@wisc.edu.
authors.forename: Ying
authors.initials: Y
authors.lastname: Ge
mesh_terms: D000818:Animals; D006801:Humans; D018482:Muscle, Skeletal / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D040901:Proteomics; D051381:Rats; D013045:Species Specificity; D013552:Swine; D014335:Tropomyosin / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D014335:Tropomyosin
keywords: Isoform; Post-translational modification; Skeletal muscle; Top-down mass spectrometry; Tropomyosin