Mammalian P4-ATPases specifically localize to the plasma membrane and the membranes of intracellular compartments. P4-ATPases contain ten transmembrane domains, and their N- and C-terminal (NT and CT) regions face the cytoplasm. Among the ATP10 and ATP11 proteins of P4-ATPases, ATP10A, ATP10D, ATP11A, and ATP11C localize to the plasma membrane, while ATP10B and ATP11B localize to late endosomes and early/recycling endosomes, respectively. We previously showed that the NT region of ATP9B is critical for its localization to the Golgi apparatus, while the CT regions of ATP11C isoforms are critical for Ca²⁺-dependent endocytosis or polarized localization at the plasma membrane. Here, we conducted a comprehensive analysis of chimeric proteins and found that the NT region of ATP10 proteins and the CT region of ATP11 proteins are responsible for their specific subcellular localization. Importantly, the ATP10B NT and the ATP11B CT regions were found to harbor a trafficking and/or targeting signal that allows these P4-ATPases to localize to late endosomes and early/recycling endosomes, respectively. Moreover, di-leucine residues in the NT region of ATP10B were required for its trafficking to endosomal compartments. These results suggest that the N- and C-terminal sequences of P4-ATPases play a key role in their intracellular trafficking.

哺乳动物P4-ATP酶特异性定位于质膜和细胞内区室的膜。P4-ATPase包含十个跨膜结构域，其N和C端（NT和CT）区域面向细胞质。在P4-ATPase的ATP10和ATP11蛋白中，ATP10A，ATP10D，ATP11A和ATP11C定位于质膜，而ATP10B和ATP11B分别定位于晚期内体和早期/回收内体。我们先前显示，ATP9B的NT区对于其定位于高尔基体至关重要，而ATP11C同工型的CT区对于Ca ²⁺至关重要依赖性内吞作用或质膜极化定位。在这里，我们对嵌合蛋白进行了全面的分析，发现ATP10蛋白的NT区和ATP11蛋白的CT区负责其特定的亚细胞定位。重要的是，发现ATP10B NT和ATP11B CT区具有运输和/或靶向信号，使这些P4-ATPase分别位于晚期内体和早期/回收内体。此外，ATP10B NT区域的双亮氨酸残基需要转运到内体区室。这些结果表明P4-ATP酶的N-和C-末端序列在其细胞内运输中起关键作用。