Activation of the epithelial sodium channel by the metalloprotease meprin β subunit.

The Epithelial Na(+) Channel (ENaC) is an apical heteromeric channel that mediates Na(+) entry into epithelial cells from the luminal cell surface. ENaC is activated by proteases that interact with the channel during biosynthesis or at the extracellular surface. Meprins are cell surface and secreted metalloproteinases of the kidney and intestine.

Syk expression in peripheral blood leukocytes, CD34+ progenitors, and CD34-derived basophils.

In human basophils from different subjects, maximum IgE-mediated histamine release and the level of syk protein expression correlate well. It is not clear when in the basophil's lifetime the set-point for syk expression is reached or how expression levels are determined for a given individual. An examination of syk expression in peripheral blood eosinophils, neutrophils, monocytes, B and T cells, DCs, and NK cells showed that with the exception of T cells, basophils were unique in expressing low levels of syk.

Protease domain glycans affect oligomerization, disulfide bond formation, and stability of the meprin A metalloprotease homo-oligomer.

The meprin A homo-oligomer is a highly glycosylated, secreted zinc metalloprotease of the astacin family and metzincin superfamily. This isoform of meprin is composed of disulfide-bonded dimers of alpha subunits that further associate to form large, secreted megadalton complexes of 10 or more subunits. The aim of this study was to determine the sites of glycan attachment and to assess their ability to affect the formation and stability of the homo-oligomer.

Intersubunit and domain interactions of the meprin B metalloproteinase. Disulfide bonds and protein-protein interactions in the MAM and TRAF domains.

Meprins, multimeric metalloproteases expressed in kidney and intestinal epithelial cells as well as in certain leukocytes and cancer cells, have the ability to hydrolyze a variety of growth factors, vasoactive peptides, cytokines, and extracellular matrix proteins. The meprin B isoform exists primarily as a cell-surface homooligomer composed of disulfide-linked, multidomain beta-subunits. To gain insight into how the tertiary and quaternary structure of meprin B affects function, the disulfide-bonding pattern and sites of domain-domain interactions were investigated using sedimentation equilibrium ultracentrifugation, cross-linking, and mass spectrometry techniques.