Rac Homologues and Compartmentalized Phosphatidylinositol 4, 5-Bisphosphate Act in a Common Pathway to Regulate Polar Pollen Tube Growth

• DOI: 10.1083/jcb.145.2.317
• Publication Date: 2002-07-26T16:45:41Z
• Authors: Benedikt Kost; Emmanuel Lemichez; Pius Spielhofer; Yan Hong; Kimberly Tolias; Christopher Carpe...; Nam-Hai Chua
• Keywords: Pleckstrin homology domain; Phosphatidylinositol 4,5-bisphosphate; Tip growth

Pollen tube cells elongate based on actin- dependent targeted secretion at the tip. Rho family small GTPases have been implicated in regulation of related processes animal and yeast cells. We functionally characterized Rac type proteins that are expressed growing pollen tubes. Expression dominant negative inhibited elongation, whereas expression constitutive active induced depolarized growth. was found to accumulate tip plasma membrane physically associate with a phosphatidylinositol monophosphate kinase (PtdIns P-K) activity. Phosphatidylinositol 4, 5-bisphosphate 5-P2), product PtdIns P-Ks, showed similar intracellular localization as Rac. pleckstrin homology (PH)-domain phospholipase C (PLC)-δ1, which binds specifically 5-P2, elongation. These results indicate 5-P2 act common pathway control polar growth provide direct evidence for function compartmentalization this process.