Abstract

Establishment of cell polarity is mediated by a series of signal-ing molecules that are asymmetrically activated or localized in the cell upon extracellular stimulation. To understand the mechanism that mediates anterior/posterior asymmetric localization of RapGAP3 during migration, we determined the minimally required amino acids in the I/LWEQ domain that cause posterior localization and found that the minimal region of the F-actin binding domain for posterior localiza-tion could, with some additional deletion at the C-terminal, localize to the anterior. Analysis of the localization and trans-location kinetics to the cell cortex of the truncated proteins suggests that the required regions for anterior/posterior lo-calization might have a preferential binding affinity to pre- existing F-actins at the rear and lateral sides of the cell or newly formed F-actins at the front of the cell, leading to dis-tinct differential sites of the cell.

• Keywords: cell polarity; cell migration; Dictyostelium; I/LWEQ domain; RapGAP3