GPI Structure and Hydrolysis by Specific Phospholipases

Gpi Phospholipase

GPIs are an abundant and ubiquitous class of eukaryotic glycolipids. Although these structures were originally discovered in the form of GPI-anchored cell surface glycoproteins, a significant proportion of the GPI synthetic output of the cell is not directed to protein anchoring but to free GPIs 18 . GPI anchors have been the subject of several reviews 1, 8, 18-21 . Preliminary structural analysis showed that the rat liver free glycolipid contained a phosphatidylinositol molecule glycosidically...

Insulin Pathway

Ipg Insulin Pathway

IGF-I-induced cell proliferation and Fos Jun expression are blocked by anti-IPG antibodies, and blockage is rescued by the addition of rat liver purified IPG-A or a myo-inositol-containing analogue 11, 57 . In summary, the activation of tyrosine kinase receptors induces the hydrolysis of GPI and the concomitant release of IPG, the mechanisms by which these two Fig. 6.3 Insulin signaling pathways. Possible routes through which insulin can promote its diverse...

TAG in Adipose Cells

Dgat1 Adipose Tissue

Adipocytes, which vary enormously in size 20-200 m in diameter , are embedded in a connective tissue matrix and are uniquely adapted to store and mobilize energy as TAG and NEFA glycerol, respectively. Surplus energy is assimilated by fat cells and stored as TAG in LD. To accommodate the TAG, adipocytes can change their diameter up to 20-fold and their volumes by several hundred-fold. Because 90 of the cell volume is constituted by LD s , the nucleus and the thin cytoplasm rim are pushed to the...

Involvement of Lipotransin

Translocation of HSL to LD might be prevented in unstimulated cells by a cytosolic inhibitor protein which interacts with HSL or by a LD-associated protein which prevents HSL gaining access to the LD surface, as has been proposed for perilipin see above . Alternatively, HSL might interact with a LD-associated docking protein upon activation, facilitating its translocation to the LD. Saltiel and coworkers have identified a novel binding-protein for HSL, called lipotransin, that fulfils several...