Binds to Rho-kinase Rok and targets it to the apical cell cortex where it mediates apical constriction (PubMed:20549743, PubMed:22493320). During embryogenic axis elongation, required for the localization to adherens junctions and the establishment of planar polarization of both Rho-kinase Rok and myosin regulatory light chain sqh (PubMed:24535826). May be involved in the assembly of microtubule arrays during cell elongation (By similarity). Monomer or homodimer (PubMed:22493320). Interacts with Rok (PubMed:22493320). Binds (via N-terminus) to F-actin (PubMed:20549743). In adherens junctions, enriched in discrete spots and in tricellular junctions (PubMed:20549743, PubMed:22493320). In adherens junctions, localization requires Rho1 GTPase activity and interaction with the F-actin cytoskeleton (PubMed:20549743, PubMed:24535826). Localization to the apical cell membrane depends on N-terminal region (PubMed:20549743). Excluded from the lateral membrane (PubMed:20549743). Expressed in the embryo (at protein level) (PubMed:20549743). Expressed in the dorsal trunk of the trachea (at protein level) (PubMed:20549743). Isoform D: Expressed in the invaginating foregut (at protein level) (PubMed:20549743). Planar polarized during axis elongation from stage 7 (at protein level) (PubMed:24535826). The ASD2 domain mediates the interaction with Rok and is required for apical constriction induction. During axis elongation in the embryo decreases localization to adherens junctions and planar polarization for both Rho-kinase Rok and myosin regulatory light chain sqh (PubMed:24535826). The mislocalization of sqh impairs the generation of sustained actomyosin contractility during cell rearrangement and can account for the reduction in the formation of multicellular rosette and convergent extension (PubMed:24535826). RNAi-mediated knockdown in the embryo decreases Rho-kinase Rok localization to adherens junctions and planar polarization during axis elongation (PubMed:24535826). Has no effect on Rho1 localization or activity (PubMed:24535826). Isoform D: RNAi-mediated knockdown in the embryo, ecreases localization to adherens junctions and planar polarization for both Rho-kinase Rok and myosin regulatory light chain sqh (PubMed:24535826). Belongs to the shroom family.