Several cell wall-bound glycosidases present in Avena sativa coleoptiles were assayed by following the hydrolysis of p-nitrophenyl-glycosides. Particular emphasis was placed on characterizing some parameters affecting the activity of beta-galactosidase. The pH optimum of this enzyme is 4.5 to 5.5; it is sensitive to copper ions and p-chloromercuribenzoate treatment and apparently has an excepti...

We have studied the effect of a post-translational modification mutation upon four developmentally regulated glycosidases of Dictyostelium discoideum. The presence of the modA mutation affects the intracellular level of these multimeric enzymes differently. The level of alpha-glucosidase is unaffected in the modA mutant. The mutant cell contains only a very small fraction of the wild type beta-...

Ribosome-inactivating proteins (RIP) are a family of plant enzymes for which a unique activity was determined: rRNAN-glycosidase at a specific universally conserved position, A4324in the case of rat ribosomes. Recently we have shown that the RIP from Saponaria officinalis have a much wider substrate specificity: they are actually polynucleotide:adenosine glycosidases. Here we extend studies on ...

The Structural Genomics Initiative promises to deliver between 10,000 and 20,000 new protein structures within the next ten years. One challenge will be to predict the functions of these proteins from their structures. Since the newly solved structures will be enriched in proteins with little sequence identity to those whose structures are known, new methods for predicting function will be requ...

The majority of proteins that traverse the secretory pathway receive asparagine (Asn)-linked glycosylations. Glycans are bulky hydrophilic modifications that serve a variety of structural and functional roles within the cell. Here, we review the recent growing knowledge on the role of Asn-linked glycans as maturation and quality-control protein tags in the early secretory pathway. The carbohydr...

Three acidic glycosidases: beta-galactosidase (beta-GAL, EC 3.2.1.23), alpha-neuraminidase (NEUR, sialidase, EC 3.2.1.18), N-acetylaminogalacto-6-sulfate sulfatase (GALNS, EC 3.1.6.4) and serine carboxypepidase cathepsin A (EC 3.4.16.1) form a functional high molecular weight complex in the lysosomes. The major constituent of this complex is cathepsin A, the so-called "lysosomal protective prot...