The conserved polybasic PSr mediates PM targeting of aPKC in Drosophila epithelia. (A) Alignment of the PSr (bold) and adjacent sequences in C1 domain from Drosophila and mammalian aPKC isoforms. Sequences are based on NCBI NP_524892.2 (DaPKC), NP_002735.3 (PKCζ), and NP_002731.4 (PKCι). Residues mutated in aPKC^KR8Q (KR8Q), aPKC^KR8A (KR8A), PKCζ^A119D (A119D), and PKCζ^AADAA (AADAA) are also shown. (B) GST fusion of PSr from PKCζ (GST-PSr), but not the nonpolybasic GST-PSr-KR8A, cosedimented with PI4P- and PIP₂-containing liposomes in vitro. (C) DaPKC::GFP (DaPKC), but not nonpolybasic DaPKC^KR8Q::GFP (KR8Q), localized to PM in embryonic and larval disc epithelia. (D) Follicular epithelial cells in ovaries from ubi-DaPKC::GFP or par-6::GFP adult females were imaged ex vivo under controlled oxygen environment. Cells are in cross-section view as indicated by the illustration at the far right. PM localization of DaPKC::GFP and Par-6::GFP were acutely inhibited by hypoxia (0.5% O₂) but recovered after reoxygenation by air (see also Videos 1 and 2). Kymographs on the right show the acute loss and recovery DaPKC::GFP or Par-6::GFP on PM during hypoxia and posthypoxia reoxygenation treatments. White boxes indicate where kymographs were sampled. Scale bars: 5 µm (C and D).