Proteins of the kidney microvillar membrane; analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and crossed immunoelectrophoresis.

A microvillar fraction was prepared from human kidney cortex. This fraction was seven to 10 times enriched in aminopeptidases N and A, gamma-glutamyltransferase, dipeptidyl peptidase IV, neutral endopeptidase and alkaline phosphatase. Dipeptidyl peptidase IV activity of human renal microvilli could be inhibited by di-isopropylphosphorofluoridate and neutral endopeptidase activity by phosphoramidon.

Organisation of the proteins of the chromaffin granule membrane.

The organisation of the protein components of bovine chromaffin granules has been investigated by labelling or digesting intact granules or broken membranes with the following reagents: lactoperoxidase/Na125I as a reagent for tyrosine residues, N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulphonic acid as a reagent for cysteine residues, pronase, and galactose oxidase/KB3H4. Following treatment, membranes were purified and washed and proteins were examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. Rather more than 60 bands were resoved, of which about 40 were relatively intense and reproducible.