Endothelial cell mitogenesis induced by LPA: inhibition by thrombospondin-1 and thrombospondin-2

Boar spermatozoa revealed three prominent resonances in the 31P-NMR spectrum of intact cells. Two of these are known to be GPC and Pi, the third is a phosphomononoester (PME), the identification of which was carried out by proton-detected 2D 1H,31P and 1H,13C chemical shift correlation experiments with gradient selection. The PME was unambiguously assigned to adenosine 5'-monophosphate (AMP). The identification was confirmed by an AMP consuming enzymatic assay. Other physiologically relevant PME's, in particular inosine 5-monophosphate (IMP) and sugar phosphates, were excluded. The intensity of the 31P signal of AMP in boar sperm extract was much higher than those of ADP and ATP, and in intact cells only AMP but no ATP was visible.