Site-directed mutagenesis of La protease. A catalytically active serine residue.

Comparative sequence analysis of Escherichia coli ATP-dependent La protease led to the suggestion that Ser679 is the catalytically active enzyme residue. Site-directed mutagenesis Ser679----Ala, investigation of the cells containing the mutant plasmid, and study of the partially purified mutant protein produced results in favour of this suggestion.

Presynaptic alpha-latrotoxin receptor components interact with protein p65 of synaptic vesicle membranes.

Purified preparations of bovine brain alpha-latrotoxin receptor contain proteins of 39 kDa and 65 kDa. Sequence analysis shows that the 65 kDa protein corresponds to p65, a synaptic vesicle membrane protein previously identified in rat synaptic vesicles, and that the 39 kDa protein is a proteolytic fragment of the 65 kDa protein. The 39 kDa and 65 kDa proteins appear in receptor samples because of their specific interaction with components of the alpha-latrotoxin receptor.