Movement of scallop myosin on Nitella actin filaments

Regulation by calcium

R. D. Vale, A. G. Szent-Gyorgyi, Michael Sheetz

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

In order to determine if Ca2+ regulates scallop myosin movement on actin, we have measured motility of scallop myosin along actin filaments using a direct visual assay. This procedure consists of covalently linking myosin to 1-μm beads and pipetting them onto a parallel array of actin filaments located on the cytoplasmic face of a Nitella internodal cell. In the absence of Ca2+, scallop myosin-coated beads exhibit no directed motion; however, in the presence of pCa2+ of greater than 5.84, these beads undergo linear translocations with average velocities of 2.0 μm/s. This Ca2+-sensitive motility requires the presence of regulatory light chains on the scallop myosin. Removal of regulatory light chains with 10 mM EDTA produces a 'desensitized' myosin, no longer sensitive to Ca2+, which moves at rates of 0.09-0.3 μs in the presence or absence of Ca2+. Readdition of regulatory light chains to preparations of desensitized myosin once again confers Ca2+-sensitive motility. The Ca2+ dependence of scallop-myosin motility shows a sharp transition, consistent with the Ca2+ activation sensitivity of the actin-activated ATPase. Furthermore, relative rates of movement of calcium-regulated myosins from various molluscan species are consistent with their respective rates of ATP hydrolysis. Thus, myosin motility along actin filaments provides a sensitive and direct assay of myosin activity and is suitable for studying myosin regulation.

Original languageEnglish (US)
Pages (from-to)6775-6778
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume81
Issue number21 I
DOIs
StatePublished - Jan 1 1984
Externally publishedYes

Fingerprint

Nitella
Pectinidae
Myosins
Actin Cytoskeleton
Calcium
Light

ASJC Scopus subject areas

  • General

Cite this

Movement of scallop myosin on Nitella actin filaments : Regulation by calcium. / Vale, R. D.; Szent-Gyorgyi, A. G.; Sheetz, Michael.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 81, No. 21 I, 01.01.1984, p. 6775-6778.

Research output: Contribution to journalArticle

@article{cd33130468a7412ab7a65b632be5a3b6,
title = "Movement of scallop myosin on Nitella actin filaments: Regulation by calcium",
abstract = "In order to determine if Ca2+ regulates scallop myosin movement on actin, we have measured motility of scallop myosin along actin filaments using a direct visual assay. This procedure consists of covalently linking myosin to 1-μm beads and pipetting them onto a parallel array of actin filaments located on the cytoplasmic face of a Nitella internodal cell. In the absence of Ca2+, scallop myosin-coated beads exhibit no directed motion; however, in the presence of pCa2+ of greater than 5.84, these beads undergo linear translocations with average velocities of 2.0 μm/s. This Ca2+-sensitive motility requires the presence of regulatory light chains on the scallop myosin. Removal of regulatory light chains with 10 mM EDTA produces a 'desensitized' myosin, no longer sensitive to Ca2+, which moves at rates of 0.09-0.3 μs in the presence or absence of Ca2+. Readdition of regulatory light chains to preparations of desensitized myosin once again confers Ca2+-sensitive motility. The Ca2+ dependence of scallop-myosin motility shows a sharp transition, consistent with the Ca2+ activation sensitivity of the actin-activated ATPase. Furthermore, relative rates of movement of calcium-regulated myosins from various molluscan species are consistent with their respective rates of ATP hydrolysis. Thus, myosin motility along actin filaments provides a sensitive and direct assay of myosin activity and is suitable for studying myosin regulation.",
author = "Vale, {R. D.} and Szent-Gyorgyi, {A. G.} and Michael Sheetz",
year = "1984",
month = "1",
day = "1",
doi = "10.1073/pnas.81.21.6775",
language = "English (US)",
volume = "81",
pages = "6775--6778",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "21 I",

}

TY - JOUR

T1 - Movement of scallop myosin on Nitella actin filaments

T2 - Regulation by calcium

AU - Vale, R. D.

AU - Szent-Gyorgyi, A. G.

AU - Sheetz, Michael

PY - 1984/1/1

Y1 - 1984/1/1

N2 - In order to determine if Ca2+ regulates scallop myosin movement on actin, we have measured motility of scallop myosin along actin filaments using a direct visual assay. This procedure consists of covalently linking myosin to 1-μm beads and pipetting them onto a parallel array of actin filaments located on the cytoplasmic face of a Nitella internodal cell. In the absence of Ca2+, scallop myosin-coated beads exhibit no directed motion; however, in the presence of pCa2+ of greater than 5.84, these beads undergo linear translocations with average velocities of 2.0 μm/s. This Ca2+-sensitive motility requires the presence of regulatory light chains on the scallop myosin. Removal of regulatory light chains with 10 mM EDTA produces a 'desensitized' myosin, no longer sensitive to Ca2+, which moves at rates of 0.09-0.3 μs in the presence or absence of Ca2+. Readdition of regulatory light chains to preparations of desensitized myosin once again confers Ca2+-sensitive motility. The Ca2+ dependence of scallop-myosin motility shows a sharp transition, consistent with the Ca2+ activation sensitivity of the actin-activated ATPase. Furthermore, relative rates of movement of calcium-regulated myosins from various molluscan species are consistent with their respective rates of ATP hydrolysis. Thus, myosin motility along actin filaments provides a sensitive and direct assay of myosin activity and is suitable for studying myosin regulation.

AB - In order to determine if Ca2+ regulates scallop myosin movement on actin, we have measured motility of scallop myosin along actin filaments using a direct visual assay. This procedure consists of covalently linking myosin to 1-μm beads and pipetting them onto a parallel array of actin filaments located on the cytoplasmic face of a Nitella internodal cell. In the absence of Ca2+, scallop myosin-coated beads exhibit no directed motion; however, in the presence of pCa2+ of greater than 5.84, these beads undergo linear translocations with average velocities of 2.0 μm/s. This Ca2+-sensitive motility requires the presence of regulatory light chains on the scallop myosin. Removal of regulatory light chains with 10 mM EDTA produces a 'desensitized' myosin, no longer sensitive to Ca2+, which moves at rates of 0.09-0.3 μs in the presence or absence of Ca2+. Readdition of regulatory light chains to preparations of desensitized myosin once again confers Ca2+-sensitive motility. The Ca2+ dependence of scallop-myosin motility shows a sharp transition, consistent with the Ca2+ activation sensitivity of the actin-activated ATPase. Furthermore, relative rates of movement of calcium-regulated myosins from various molluscan species are consistent with their respective rates of ATP hydrolysis. Thus, myosin motility along actin filaments provides a sensitive and direct assay of myosin activity and is suitable for studying myosin regulation.

UR - http://www.scopus.com/inward/record.url?scp=0343286277&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0343286277&partnerID=8YFLogxK

U2 - 10.1073/pnas.81.21.6775

DO - 10.1073/pnas.81.21.6775

M3 - Article

VL - 81

SP - 6775

EP - 6778

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 21 I

ER -