Membrane-Bound and cytosolic forms of heterotrimeric G proteins in young and adult rat myocardium: influence of neonatal hypo- and hyperthyroidism
Language English Country United States Media print
Document type Comparative Study, Journal Article, Research Support, Non-U.S. Gov't
PubMed
11527147
DOI
10.1002/jcb.1157
PII: 10.1002/jcb.1157
Knihovny.cz E-resources
- MeSH
- Cytosol enzymology MeSH
- Heterotrimeric GTP-Binding Proteins analysis MeSH
- Hyperthyroidism chemically induced enzymology pathology MeSH
- Hypothyroidism chemically induced enzymology pathology MeSH
- Isoenzymes analysis MeSH
- Rats MeSH
- Membrane Proteins analysis MeSH
- Myocardium enzymology pathology MeSH
- Animals, Newborn MeSH
- Protein Subunits MeSH
- Rats, Wistar MeSH
- Propylthiouracil toxicity MeSH
- Subcellular Fractions enzymology MeSH
- Triiodothyronine administration & dosage MeSH
- Age Factors MeSH
- Organ Size MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
- Names of Substances
- Heterotrimeric GTP-Binding Proteins MeSH
- Isoenzymes MeSH
- Membrane Proteins MeSH
- Protein Subunits MeSH
- Propylthiouracil MeSH
- Triiodothyronine MeSH
Membrane and cytosolic fractions prepared from ventricular myocardium of young (21-day-old) hypo- or hyperthyroid rats and adult (84-day-old) previously hypo- or hyperthyroid rats were analyzed by immunoblotting with specific anti-G-protein antibodies for the relative content of Gs alpha, Gi alpha/Go alpha, Gq alpha/G11 alpha, and G beta. All tested G protein subunits were present not only in myocardial membranes but were at least partially distributed in the cytosol, except for Go alpha2, and G11 alpha. Cytosolic forms of the individual G proteins represented about 5-60% of total cellular amounts of these proteins. The long (Gs alpha-L) isoform of Gs alpha prevailed over the short (Gs alpha-S) isoform in both crude myocardial membranes and cytosol. The Gs alpha-L/Gs alpha-S ratio in membranes as well as in cytosol increased during maturation due to a substantial increase in Gs alpha-L. Interestingly, whereas the amount of membrane-bound Gi alpha/Go alpha and Gq alpha/G11 alpha proteins tend to lower during postnatal development, cytosolic forms of these G proteins mostly rise. Neonatal hypothyroidism reduced the amount of myocardial Gs alpha and increased that of Gi alpha/Go alpha proteins. By contrast, neonatal hyperthyroidism increased expression of Gs alpha and decreased that of Gi alpha and G11 alpha in young myocardium. Changes in G protein content induced by neonatal hypo- and hyperthyroidism in young rat myocardium were restored in adulthood. Alterations in the membrane-cytosol balance of G protein subunits associated with maturation or induced by altered thyroid status indicate physiological importance of cytosolic forms of these proteins in the rat myocardium.
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