FIGURE 2. Rab family small GTP-binding proteins identified in AQP2-vesicles from inner medullary collecting duct. Rab GTPases and their effectors coordinate vesicle transport. They are involved in vesicle budding, transport, docking, and fusion. All Rab proteins listed were identified in the AQP2-containing vesicles except Rab3. CCV, clathrin-coated vesicle; EE, early endosome; ER, endoplasmic reticulum; LE, late endosome; RE, recycling endosome. Trairak Pisitkun, Jason D. Hoffert, Ming-Jiun Yu, and Mark A. Knepper. Tandem Mass Spectrometry in Physiology. Physiology 22: 390-400, 2007