Hostname: page-component-89b8bd64d-n8gtw Total loading time: 0 Render date: 2026-05-13T06:33:25.340Z Has data issue: false hasContentIssue false

The role of microtubules and inositol triphosphate induced Ca2+ release in the tyrosine phosphorylation of mitogen-activated protein kinase in extracts of Xenopus laevis oocytes

Published online by Cambridge University Press:  26 September 2008

N.S. Duesbery*
Affiliation:
Department of Zoology, University of Toronto, Toronto, Canada
Y. Masui
Affiliation:
Department of Zoology, University of Toronto, Toronto, Canada
*
N.S. Duesbery, Department of Zoology, University of Toronto, Toronto, Canada M5S 1A1. Telephone: (416) 978-3493. Fax; (416) 978-8532 e-mail: duesbery@zoo.toronto.edu.

Summary

Microsomal fractions of Xenopus oocytes release preloaded 45Ca2+ when treated with inositol triphosphate (InsP3). The effective concentration of InsP3 required for half-maximal release (EC50) is 59 nM and maximal release occurs at ∼ 2 μM InsP3. Uptake and release of 45Ca2+ are not altered by the catalytic subunit of protein kinase A, dibutyrl cyclic adenosine monophosphate, protein kinase A peptide inhibitor or nocodazole. In contrast, taxol decreases the sensitivity of the microsomal fraction to InsP3, shifting the EC50 for InsP3-induced Ca2+ release from 59 to 259 nM. In lysates of oocytes, InsP3-induced Ca2+ release causes the tyrosine phorphorylation of a 42000 (Mr 42k) protein identified as 42k mitogen-activated protein (MAP) kinase. InsP3-induced tyrosine phosphorylation of MAP kinase is prevented by BAPTA and taxol, but not by nocodazole. Thus, microtubule polymerisation modifies InsP3-induced Ca2+ release, thereby inhibiting phosphorylation of MAP kinase.

Information

Type
Article
Copyright
Copyright © Cambridge University Press 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable