Tissue type drives gene splicing choice
European researchers have identified a gene in the model plant, Arabidopsis thaliana, that encodes for different proteins in different tissues. The gene, ZIFL1 (zinc-induced facilitator-like1) encodes an auxin transporter polypeptide in root tissue and a protein that confers drought tolerance in leaf tissue. The two polypeptide sequences produced by alternative splicing of the ZIFL1 RNA product differ in two amino acid residues that introduce an early stop codon. The longer protein, ZIFL1.1, is expressed in root tissue tonoplast membranes where it regulates polar auxin transport by modulating potassium and proton fluxes. The truncated form, ZIFL1.3, is expressed in leaf stomatal guard cell plasma membranes where it regulates stomatal closure. As yet unidentified tissue-specific factors influence the splicing of the ZIFL1 RNA into the form that confers the biological role necessary for that tissue, the researchers suggest. Details of the study have been published in the journal, The Plant Cell.