pus IX81 inverted microscope equipped with Olympus UPlanApo 406 1.00 NA oil objective. F-Ab40 was imaged using the 488-nm line of a 150 mW multi-line 19276073 Melles-Griot argon-ion laser with emission collection ranging from 520539 nm. AF647-CT or AF633-Trf was imaged using a 5 mW 633 nm Melles-Griot argon-ion laser with emission collection ranging from 650 750 nm. Photomultiplier, gain, offset, and confocal aperture settings were maintained the same for all images. Cellular Uptake of Ab Proteins 17 Cellular Uptake of Ab Proteins 18 Cellular Uptake of Ab Proteins Flow cytometry FACScan was equipped with 488 nm laser and 530/30 band-pass filter to analyze F-Ab40 or F-Ab42 as well as 633 nm laser and 660/20 band-pass filter to analyze AF633-Trf. Each unfixed cell sample was observed to have two distinct populations of cells, one with low and the other with high forward scatter. When treated with live and dead cell markers, 22315414 the population of cells with high forward scatter contained more than 90% viable cells. The cellular fluorescence from this cell population was presented as histograms along with relevant statistical values such as geometric mean and coefficient of variance. Acknowledgments We thank: Dr. Dan McCormick and Jane A. Petersen for extending their technical expertise in synthesizing the Ab40; and fluorescein labeled Ab40 and 42; Geoffry L. Curran for his assistance in harvesting brain tissue from mice and 125I labeling of Ab40; Jarred Nesbitt and Dr. Anthony Windebank for providing PC12 cells; and Jennifer Scott for her excellent secretarial assistance. Protein kinases are key regulators of cellular function that act via phosphorylating target proteins thus directing their activity, location and function. Serum- and glucocorticoid-regulated protein kinases are members of the AGC kinase subfamily and are involved in signal cascades which are regulated in mammals by serum and glucocorticoid hormones. Additionally, the mammalian SGK is activated in response to the follicle-stimulating hormone that is produced during brain damage and the transfection of mammary epithelial cells with the p53 transcription factor. The threonine residue, located on the SGK activation loop of the catalytic domain, is phosphorylated by the 3-phosphoinositide-dependent protein kinase-1, which serves as a central integrator of signaling cascades. Additional PDK1 targets include the p70 S6 kinase, PKC isoforms, PKB and SGK. Two S. cerevisiae genes, ypk1 and ypk2, were identified as SGK homologues. The ypk1 was shown to confer resistance to ISP-1, an inhibitor of sphingolipid synthesis. Complementation of the Dypk1 S. cerevisiae strain with the mammalian SGK restored viability. The S. cerevisiae pkh1 protein kinase possesses a catalytic buy NVP-BHG712 domain that resembles the mammalian PDK1 catalytic domain. In S. cerevisiae, Pkh1 is essential. Complementation of the Dpkh1 with PDK1 restored viability, while Ypk1 was also demonstrated to be phosphorylated by Pkh1 on the Thr504 residue, indicating that PDK1 and pkh1 are functional homologues. Sphingolipids are essential components of eukaryotic cells providing membrane structure, acting as secondary messengers and interacting with sterols to form lipid-rafts. In eukaryotic cells, sphingolipids are also involved in important cellular processes such as endocytosis, intracellular trafficking of proteins and lipids, cell cycle 
control, and the heat shock response. In S. cerevisiae Ypk1 regulates two flipase protein kinases, Fpk1 an
