Distribution of isoelectric variants of the 17,000-dalton myosin light chain in mammalian smooth muscle

Debra Helper, J. A. Lash, D. R. Hathaway

Research output: Contribution to journalArticle

71 Citations (Scopus)

Abstract

Isoelectric focusing of purified vascular smooth muscle myosin revealed to variants of the 17,000-dalton light chain subunits. The isoelectric points of the light chain variants were determined to be 4.13 (LC(17a)) and 4.19 (LC(17b)). Tryptic peptide maps of the two species of light chain generated by reverse-phase high performance liquid chromatography disclosed small but obvious differences in peptide composition while amino acid analyses of the variants were quite similar. Two-dimensional electrophoresis of extracts from various mammalian smooth muscles revealed tissue-specific differences in the relative content of LC(17a) and LC(17b). Vascular (aorta, carotid, and pulmonary artery) muscles and tracheal smooth muscle contained both light chain variants while smooth muscle of the gastrointestinal tract (stomach and jejunum) contained LC(17a) only. The actin-activated Mg2+-ATPase activities of both phosphorylated and nonphosphorylated stomach (LC(17b) = 0) and aortic (LC(17b) = 40%) myosins were compared. In the presence of saturating tropomyosin, a 2-fold difference in V(max) was measured: phosphorylated, aortic, 0.119 ± 0.009 versus stomach, 0.239 ± 0.012 μmol of PO4 liberated/min/mg of myosin; non-phosphorylated, aortic, 0.065 ± 0.004 versus stomach, 0.123 ± 0.004 μmol of PO4 liberated/min/mg of myosin. In addition, the V(max) of myosin subfragment-1 ATPase from bovine aortic, pulmonary artery, and stomach myosins (LC(17b) contents, 40, 20, and 0%, respectively) was found to decrease in direct proportion to the LC(17b) content. Our results suggest that isoforms of the 17,000-dalton light chain subunits of mammalian smooth muscle myosin could play an important role in modulating actomyosin ATPase activity.

Original languageEnglish
Pages (from-to)15748-15753
Number of pages6
JournalJournal of Biological Chemistry
Volume263
Issue number30
StatePublished - 1988

Fingerprint

Myosin Light Chains
Myosins
Smooth Muscle
Muscle
Stomach
Smooth Muscle Myosins
Light
Pulmonary Artery
Myosin Subfragments
Ca(2+) Mg(2+)-ATPase
Tropomyosin
Peptides
High performance liquid chromatography
Muscles
Electrophoresis
Isoelectric Point
Isoelectric Focusing
Reverse-Phase Chromatography
Adenosine Triphosphatases
Jejunum

ASJC Scopus subject areas

  • Biochemistry

Cite this

Distribution of isoelectric variants of the 17,000-dalton myosin light chain in mammalian smooth muscle. / Helper, Debra; Lash, J. A.; Hathaway, D. R.

In: Journal of Biological Chemistry, Vol. 263, No. 30, 1988, p. 15748-15753.

Research output: Contribution to journalArticle

@article{24f7fbebd4a54e6487c725f69e2bb2c5,
title = "Distribution of isoelectric variants of the 17,000-dalton myosin light chain in mammalian smooth muscle",
abstract = "Isoelectric focusing of purified vascular smooth muscle myosin revealed to variants of the 17,000-dalton light chain subunits. The isoelectric points of the light chain variants were determined to be 4.13 (LC(17a)) and 4.19 (LC(17b)). Tryptic peptide maps of the two species of light chain generated by reverse-phase high performance liquid chromatography disclosed small but obvious differences in peptide composition while amino acid analyses of the variants were quite similar. Two-dimensional electrophoresis of extracts from various mammalian smooth muscles revealed tissue-specific differences in the relative content of LC(17a) and LC(17b). Vascular (aorta, carotid, and pulmonary artery) muscles and tracheal smooth muscle contained both light chain variants while smooth muscle of the gastrointestinal tract (stomach and jejunum) contained LC(17a) only. The actin-activated Mg2+-ATPase activities of both phosphorylated and nonphosphorylated stomach (LC(17b) = 0) and aortic (LC(17b) = 40{\%}) myosins were compared. In the presence of saturating tropomyosin, a 2-fold difference in V(max) was measured: phosphorylated, aortic, 0.119 ± 0.009 versus stomach, 0.239 ± 0.012 μmol of PO4 liberated/min/mg of myosin; non-phosphorylated, aortic, 0.065 ± 0.004 versus stomach, 0.123 ± 0.004 μmol of PO4 liberated/min/mg of myosin. In addition, the V(max) of myosin subfragment-1 ATPase from bovine aortic, pulmonary artery, and stomach myosins (LC(17b) contents, 40, 20, and 0{\%}, respectively) was found to decrease in direct proportion to the LC(17b) content. Our results suggest that isoforms of the 17,000-dalton light chain subunits of mammalian smooth muscle myosin could play an important role in modulating actomyosin ATPase activity.",
author = "Debra Helper and Lash, {J. A.} and Hathaway, {D. R.}",
year = "1988",
language = "English",
volume = "263",
pages = "15748--15753",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "30",

}

TY - JOUR

T1 - Distribution of isoelectric variants of the 17,000-dalton myosin light chain in mammalian smooth muscle

AU - Helper, Debra

AU - Lash, J. A.

AU - Hathaway, D. R.

PY - 1988

Y1 - 1988

N2 - Isoelectric focusing of purified vascular smooth muscle myosin revealed to variants of the 17,000-dalton light chain subunits. The isoelectric points of the light chain variants were determined to be 4.13 (LC(17a)) and 4.19 (LC(17b)). Tryptic peptide maps of the two species of light chain generated by reverse-phase high performance liquid chromatography disclosed small but obvious differences in peptide composition while amino acid analyses of the variants were quite similar. Two-dimensional electrophoresis of extracts from various mammalian smooth muscles revealed tissue-specific differences in the relative content of LC(17a) and LC(17b). Vascular (aorta, carotid, and pulmonary artery) muscles and tracheal smooth muscle contained both light chain variants while smooth muscle of the gastrointestinal tract (stomach and jejunum) contained LC(17a) only. The actin-activated Mg2+-ATPase activities of both phosphorylated and nonphosphorylated stomach (LC(17b) = 0) and aortic (LC(17b) = 40%) myosins were compared. In the presence of saturating tropomyosin, a 2-fold difference in V(max) was measured: phosphorylated, aortic, 0.119 ± 0.009 versus stomach, 0.239 ± 0.012 μmol of PO4 liberated/min/mg of myosin; non-phosphorylated, aortic, 0.065 ± 0.004 versus stomach, 0.123 ± 0.004 μmol of PO4 liberated/min/mg of myosin. In addition, the V(max) of myosin subfragment-1 ATPase from bovine aortic, pulmonary artery, and stomach myosins (LC(17b) contents, 40, 20, and 0%, respectively) was found to decrease in direct proportion to the LC(17b) content. Our results suggest that isoforms of the 17,000-dalton light chain subunits of mammalian smooth muscle myosin could play an important role in modulating actomyosin ATPase activity.

AB - Isoelectric focusing of purified vascular smooth muscle myosin revealed to variants of the 17,000-dalton light chain subunits. The isoelectric points of the light chain variants were determined to be 4.13 (LC(17a)) and 4.19 (LC(17b)). Tryptic peptide maps of the two species of light chain generated by reverse-phase high performance liquid chromatography disclosed small but obvious differences in peptide composition while amino acid analyses of the variants were quite similar. Two-dimensional electrophoresis of extracts from various mammalian smooth muscles revealed tissue-specific differences in the relative content of LC(17a) and LC(17b). Vascular (aorta, carotid, and pulmonary artery) muscles and tracheal smooth muscle contained both light chain variants while smooth muscle of the gastrointestinal tract (stomach and jejunum) contained LC(17a) only. The actin-activated Mg2+-ATPase activities of both phosphorylated and nonphosphorylated stomach (LC(17b) = 0) and aortic (LC(17b) = 40%) myosins were compared. In the presence of saturating tropomyosin, a 2-fold difference in V(max) was measured: phosphorylated, aortic, 0.119 ± 0.009 versus stomach, 0.239 ± 0.012 μmol of PO4 liberated/min/mg of myosin; non-phosphorylated, aortic, 0.065 ± 0.004 versus stomach, 0.123 ± 0.004 μmol of PO4 liberated/min/mg of myosin. In addition, the V(max) of myosin subfragment-1 ATPase from bovine aortic, pulmonary artery, and stomach myosins (LC(17b) contents, 40, 20, and 0%, respectively) was found to decrease in direct proportion to the LC(17b) content. Our results suggest that isoforms of the 17,000-dalton light chain subunits of mammalian smooth muscle myosin could play an important role in modulating actomyosin ATPase activity.

UR - http://www.scopus.com/inward/record.url?scp=0023756765&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023756765&partnerID=8YFLogxK

M3 - Article

C2 - 2971667

AN - SCOPUS:0023756765

VL - 263

SP - 15748

EP - 15753

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 30

ER -