Abstract
Pollen tube growth is dependent on a dynamic actin cytoskeleton, suggesting that actin-regulating proteins are involved. We have examined the regulation of the lily pollen-specific actin-depolymerizing factor (ADF) LlADF1. Its actin binding and depolymerizing activity is pH sensitive, inhibited by certain phosphoinositides, but not controlled by phosphorylation. Compared with its F-actin binding properties, its low activity in depolymerization assays has been used to explain why pollen ADF decorates F-actin in pollen grains. This low activity is incompatible with a role in increasing actin dynamics necessary to promote pollen tube growth. We have identified a plant homolog of actin-interacting protein, AIP1, which enhances the depolymerization of F-actin in the presence of LlADF1 by approximately 60%. Both pollen ADF and pollen AIP1 bind F-actin in pollen grains but are mainly cytoplasmic in pollen tubes. Our results suggest that together these proteins remodel actin filaments as pollen grains enter and exit dormancy.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actin Depolymerizing Factors
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Actins / metabolism*
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Arabidopsis / genetics
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Arabidopsis / metabolism
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism
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Brassica napus / genetics
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Brassica napus / metabolism
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cloning, Molecular
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Conserved Sequence / genetics
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Cytoskeleton / metabolism
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Destrin
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Gene Expression Regulation, Plant / genetics
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Hydrogen-Ion Concentration
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Lilium / genetics
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Lilium / metabolism
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Magnoliopsida / genetics*
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Magnoliopsida / metabolism
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Microfilament Proteins / drug effects
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Microfilament Proteins / genetics*
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Microfilament Proteins / metabolism
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Phospholipids / pharmacology
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Phosphorylation
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Phylogeny
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Plant Proteins / genetics
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Plant Proteins / metabolism
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Pollen / genetics
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Pollen / growth & development*
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Pollen / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Two-Hybrid System Techniques
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Zea mays / genetics
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Zea mays / metabolism
Substances
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AIP1 protein, Arabidopsis
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Actin Depolymerizing Factors
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Actins
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Arabidopsis Proteins
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Carrier Proteins
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Destrin
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Microfilament Proteins
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Phospholipids
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Plant Proteins
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actin interacting protein 1