“…11 1985), secretory granules (Wiedemann et al, 1996), synaptic vesicles (Wiedemann et al, 1998), Golgi (Jergil and Sundler, 1983;Cockcroft et al, 1985) and glucose transporter 4-containing transport vesicles (Del Vecchio and Pilch, 1991), little is known about the subcellular localization of PI4K proteins in neurons and neuroendocrine cells (Balla et al, 2000). Different types of PI4Ks have been cloned and characterized from yeast and mammalian cells (Balla, 1998;Fruman et al, 1998;Nakagawa et al, 1996a;Nakagawa et al, 1996b;Meyers and Cantley, 1997) and it is clear from these studies that different isoforms of the PI4K family may synthesize different pools of polyphosphoinositides that in turn modulate different cellular functions (De Camilli et al, 1996;Anderson et al, 1999;Balla, 2001;Cremona and DeCamilli, 2001). The localization of distinct kinase isoforms to specific sites in cellular compartments helps to explain the different roles that phosphoinositides play in cells.…”