| An IP3-activated Ca2+ channel regulates fungal tip growth. | |
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MedLine Citation:
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PMID: 12432087 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Hyphal extension in fungi requires a tip-high Ca(2+) gradient, which is generated and maintained internally by inositol (1,4,5)-trisphosphate (IP(3))-induced Ca(2+) release from tip-localized vesicles and subapical Ca(2+) sequestration. Using the planar bilayer method we demonstrated the presence of two types of IP(3)-activated Ca(2+) channels in Neurospora crassa membranes with different conductances: one low (13 picosiemens), the other high (77 picosiemens). On sucrose density gradients the low conductance channel co-localized with endoplasmic reticulum and plasma membrane, and the high conductance channel co-localized with vacuolar membranes. We correlated the effect of inhibitors on channel activity with their effect on hyphal growth and Ca(2+) gradients. The inhibitor of IP(3)-induced Ca(2+) release, 2-aminoethoxidiphenylborate (2-APB), inhibits both channels, while heparin, 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate, hydrochloride (TMB-8) and dantrolene inhibit only the large conductance channel. Because 2-APB inhibits hyphal growth and dissipates the tip-high cytosolic [Ca(2+)] gradient, whereas heparin microinjection, TMB-8 and dantrolene treatments do not affect growth, we suggest that the small conductance channel generates the obligatory tip-high Ca(2+) gradient during hyphal growth. Since IP(3) production must be catalyzed by tip-localized phospholipase C, we show that a number of phospholipase C inhibitors [neomycin, 1-[6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]- 1H-pyrrole-2,5-dione (U-73122) (but not the inactive pyrrolidine U-73343), 3-nitrocoumarin] inhibit hyphal growth and affect, similarly to 2-APB, the location of vesicular Ca(2+) imaged by chlortetracycline staining. |
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Authors:
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Lorelei B Silverman-Gavrila; Roger R Lew |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of cell science Volume: 115 ISSN: 0021-9533 ISO Abbreviation: J. Cell. Sci. Publication Date: 2002 Dec |
Date Detail:
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Created Date: 2002-11-14 Completed Date: 2003-07-16 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0052457 Medline TA: J Cell Sci Country: England |
Other Details:
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Languages: eng Pagination: 5013-25 Citation Subset: IM |
Affiliation:
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Biology Department, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Calcium Channels
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physiology* Fluorescence Inositol 1,4,5-Trisphosphate / physiology* Lipid Bilayers Membrane Potentials Neurospora crassa / growth & development* Type C Phospholipases / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Calcium Channels; 0/Lipid Bilayers; 85166-31-0/Inositol 1,4,5-Trisphosphate; EC 3.1.4.-/Type C Phospholipases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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