Macrophages have long been known to secrete a Phospholipase A(2) with an acidic pH optimum in response to phagocytic stimuli. However, the enzyme or enzymes responsible for this activity have not been identified. We report that mouse alveolar macrophages release lysosomal phospholipase A(2) (LPLA(2)) into the medium of cultured cells following stimulation with zymosan. The release of the enzyme...

Numerous plants and fungi produce mannitol, which may serve as an osmolyte or metabolic store; furthermore, mannitol also acts as a powerful quencher of reactive oxygen species (ROS). Some phytopathogenic fungi use mannitol to stifle ROS-mediated plant resistance. Mannitol is essential in pathogenesis to balance cell reinforcements produced by both plants and animals. Mannitol likewise serves a...

The localization of acid hydrolases was examined in Chinese hamster ovary cells with defective mannose 6-phosphate receptors; these mutants had been shown to exhibit reduced uptake and altered binding of exogenously added acid hydrolase (Robbins, A. R., Myerowitz, R., Youle, R. J., Murray, G. J., and Neville, D. M., Jr. (1981) J. Biol. Chem. 256, 10618-10622). Cells were grown in the presence o...

The most frequent disorder of glycosylation, PMM2-CDG, is caused by a deficiency of phosphomannomutase activity. In humans two paralogous enzymes exist, both of them require mannose 1,6-bis-phosphate or glucose 1,6-bis-phosphate as activators, but only phospho-mannomutase1 hydrolyzes bis-phosphate hexoses. Mutations in the gene encoding phosphomannomutase2 are responsible for PMM2-CDG. Although...

A family of six specific insulin-like growth factor binding proteins (IGFBPs) modulates the biological actions of the insulin-like growth factors, IGF-I and IGF-II. In the present study, we determined the binding affinity of purified human IGFBPs 1-6 for recombinant human IGF-II mutants whose binding to IGF-I, IGF-II/mannose 6-phosphate, and insulin receptors was previously reported (Sakano, K....

Phosphoglucose isomerase from the crenarchaeon Pyrobaculum aerophilum (PaPGI/PMI) shows virtually no sequence similarity to its counterparts from bacterial and eukaryotic sources and belongs to a unique group within the PGI superfamily. Whereas conventional PGIs show strict substrate specificity for glucose 6-phosphate and fructose 6-phosphate, PaPGI/PMI can also catalyse the isomerization of m...

A particulate fraction from porcine aorta catalyzed the incorporation of N-acetylglucosamine (GlcNAc) from UDP-[3H]GlcNAc into both GlcNAc-pyrophosphorylpolyprenol and GlcNAc-GlcNAc-pyrophosphorylpolyprenol. This transfer utilized endogenous lipid and required a divalent cation. Mn2+ was the best metal ion and was optimum at 2.3 mM. This same particulate fraction was previously shown to transfe...