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United States Department of Agriculture

Agricultural Research Service

Title: A Leucine-Rich Repeat Region Is Conserved in Pollen Extensin-Like (Pex) Proteins in Monocots and Dicots

Authors
item Stratford, Suzanne - COLORADO STATE FT COLLINS
item Barnes, William - COLORADO STATE FT COLLINS
item Hohorst, Diane - COLORADO STATE FT COLLINS
item Sagert, Jason - COLORADO STATE FT COLLINS
item Cotter, Robyn - USDA/UCB PGEC
item Gikybuewsju, Alice - COLORADO STATE FT COLLINS
item Showalter, Allan - OHIO UNIVERSITY, ATHENS
item McCormick, Sheila
item Bedinger, Patricia - COLORADO STATE FT COLLINS

Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2001
Publication Date: May 1, 2001

Interpretive Summary: To determine what protein domains of a pollen tube wall-associated glycoprotein might be important for function, we compared seuqences from several plants. The extracullar parts of the Pex proteins are highly conserved. Although the extensin domains in the maize and tomato proteins vary in length and in amino acid sequence, they are likely to be structurally conserved. The presence of a conserved LRRs in the Pex proteins strongly suggests that this motif is involved in the binding of a specific ligand during pollen tube growth.

Technical Abstract: We previously isolated a pollen-specific gene encoding a pollen tube wall-associated glycoprotein with a globular domain and an extensin domain from maize (mPex1). To evaluate which protein domains might be important for function, we isolated a second monocot gene (mPex2) and a dicot gene (tPex). Each gene encodes a signal sequence, an N-terminal globular domain comprised of a variable region, a leucine-rich repeat (LRR) with an adjacent cysteine-rich region, a transition region and an extensin-like C-terminal domain. The LRRs of the maize and tomato Pex proteins are highly conserved. Although the extensin domains in the maize and tomato proteins vary in length and in amino acid sequence, they are likely to be structurally conserved. Additional putative Pex gene sequences were identified by either GenBank search (Arabidopsis) or PCR (sorghum and potato); all encode conserved LRRs. The presence of a conserved LRR in the known and potential Pex proteins strongly suggests that this motif is involved in the binding of a specific ligand during pollen tube growth. Gene expression studies using RNA and protein blotting as well as promoter-reporter gene fusions in transient and stable transformation indicate that the tomato Pex gene is pollen-specific.

Last Modified: 9/21/2014
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