| Identification and functional significance of troponin I isoforms in neonatal rat heart myofibrils. | |
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MedLine Citation:
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PMID: 1934354 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We investigated the mechanism(s) responsible for differences in the effects of acidic pH on Ca2+ activation of the activity of adult and neonatal rat heart myofilaments. Studies on preparations of myofilaments reconstituted with adult troponin-tropomyosin (Tn-Tm) and either adult or neonatal thick filaments indicated that the difference in effect of acidic pH is related to differences in Tn-Tm and not other myofilament proteins. Immunoblotting analysis showed that development of the rat heart myofibrils is associated with isoform switching from slow skeletal TnI to cardiac TnI and from a slow mobility isoform of TnT (TnT1) to a faster Mr isoform (TnT2. Expression of slow skeletal TnI was associated with a relative insensitivity of myofilament Ca2+ activation to deactivation by acidic pH. Moreover, the effect of acidic pH on Ca2+ activation of ATPase activity of soleus myofibrils, which contain cardiac TnC and slow skeletal TnI, was essentially the same as the effect of acidic pH on rat cardiac myofibrils in the early neonatal period. Neonatal myofilaments also contained a relative abundance of a set of polypeptides copurifying with the thin filaments. We have identified these proteins as histones. The relative amount of histones among a variety of preparations from different species was not correlated with the pH sensitivity of myofibrillar Ca2+ activation. Shifts in TnT isoforms among these species were also not correlated with an altered response to acidic pH. Our data provide evidence in support of the hypothesis that the relative insensitivity of neonatal myofilament activity to acidic pH is due to the presence of slow skeletal TnI in the thin-filament regulatory complex. |
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Authors:
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A F Martin; K Ball; L Z Gao; P Kumar; R J Solaro |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Circulation research Volume: 69 ISSN: 0009-7330 ISO Abbreviation: Circ. Res. Publication Date: 1991 Nov |
Date Detail:
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Created Date: 1991-11-27 Completed Date: 1991-11-27 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0047103 Medline TA: Circ Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1244-52 Citation Subset: IM |
Affiliation:
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Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Ohio. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acids
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metabolism Animals Animals, Newborn Blotting, Western Calcium / physiology Electrophoresis, Polyacrylamide Gel Histones / metabolism Hydrogen-Ion Concentration Isomerism Myocardium / metabolism* Myofibrils / metabolism* Peptides / chemistry, metabolism Rabbits Rats Rats, Inbred Strains Troponin / metabolism* Troponin I |
| Grant Support | |
ID/Acronym/Agency:
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P01 HL-22619-IIIB/HL/NHLBI NIH HHS; R01 HL-22231/HL/NHLBI NIH HHS; T32 HL-07692/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Acids; 0/Histones; 0/Peptides; 0/Troponin; 0/Troponin I; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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