Loop 2 of Limulus myosin III is phosphorylated by protein kinase A and autophosphorylation

Karen Kempler, J. Tóth, Roxanne Yamashita, Gretchen Mapel, Kimberly Robinson, Helene Cardasis, Stanley Stevens, James R. Sellers, Barbara Anne Battelle

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Little is known about the functions of class III unconventional myosins although, with an N-terminal kinase domain, they are potentially both signaling and motor proteins. Limulus myosin III is particularly interesting because it is a phosphoprotein abundant in photoreceptors that becomes more heavily phosphorylated at night by protein kinase A. This enhanced nighttime phosphorylation occurs in response to signals from an endogenous circadian clock and correlates with dramatic changes in photoreceptor structure and function. We seek to understand the role of Limulus myosin III and its phosphorylation in photoreceptors. Here we determined the sites that become phosphorylated in Limulus myosin III and investigated its kinase, actin binding, and myosin ATPase activities. We show that Limulus myosin III exhibits kinase activity and that a major site for both protein kinase A and autophosphorylation is located within loop 2 of the myosin domain, an important actin binding region. We also identify the phosphorylation of an additional protein kinase A and autophosphorylation site near loop 2, and a predicted phosphorylation site within loop 2. We show that the kinase domain of Limulus myosin III shares some pharmacological properties with protein kinase A, and that it is a potential opsin kinase. Finally, we demonstrate that Limulus myosin III binds actin but lacks ATPase activity. We conclude that Limulus myosin III is an actin-binding and signaling protein and speculate that interactions between actin and Limulus myosin III are regulated by both second messenger mediated phosphorylation and autophosphorylation of its myosin domain within and near loop 2.

Original languageEnglish
Pages (from-to)4280-4293
Number of pages14
JournalBiochemistry
Volume46
Issue number14
DOIs
Publication statusPublished - Apr 10 2007

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Myosin Type III
Horseshoe Crabs
Cyclic AMP-Dependent Protein Kinases
Phosphorylation
Myosins
Actins
Phosphotransferases
G-Protein-Coupled Receptor Kinase 1
Microfilament Proteins
Phosphoproteins
Circadian Clocks
Second Messenger Systems
Adenosine Triphosphatases
Clocks
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Kempler, K., Tóth, J., Yamashita, R., Mapel, G., Robinson, K., Cardasis, H., ... Battelle, B. A. (2007). Loop 2 of Limulus myosin III is phosphorylated by protein kinase A and autophosphorylation. Biochemistry, 46(14), 4280-4293. https://doi.org/10.1021/bi062112u

Loop 2 of Limulus myosin III is phosphorylated by protein kinase A and autophosphorylation. / Kempler, Karen; Tóth, J.; Yamashita, Roxanne; Mapel, Gretchen; Robinson, Kimberly; Cardasis, Helene; Stevens, Stanley; Sellers, James R.; Battelle, Barbara Anne.

In: Biochemistry, Vol. 46, No. 14, 10.04.2007, p. 4280-4293.

Research output: Contribution to journalArticle

Kempler, K, Tóth, J, Yamashita, R, Mapel, G, Robinson, K, Cardasis, H, Stevens, S, Sellers, JR & Battelle, BA 2007, 'Loop 2 of Limulus myosin III is phosphorylated by protein kinase A and autophosphorylation', Biochemistry, vol. 46, no. 14, pp. 4280-4293. https://doi.org/10.1021/bi062112u
Kempler K, Tóth J, Yamashita R, Mapel G, Robinson K, Cardasis H et al. Loop 2 of Limulus myosin III is phosphorylated by protein kinase A and autophosphorylation. Biochemistry. 2007 Apr 10;46(14):4280-4293. https://doi.org/10.1021/bi062112u
Kempler, Karen ; Tóth, J. ; Yamashita, Roxanne ; Mapel, Gretchen ; Robinson, Kimberly ; Cardasis, Helene ; Stevens, Stanley ; Sellers, James R. ; Battelle, Barbara Anne. / Loop 2 of Limulus myosin III is phosphorylated by protein kinase A and autophosphorylation. In: Biochemistry. 2007 ; Vol. 46, No. 14. pp. 4280-4293.
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