cathepsin-B (APP alpha-secretase)

Function

• thiol protease with role in intracellular degradation & turnover of proteins
• implicated in tumor invasion & metastasis
• hydrolysis of proteins with broad specificity for peptide bonds
• preferentially cleaves -Arg-Arg-|-Xaa bonds in small molecule substrates (thus differing from cathepsin L)
• endopeptidase, & peptidyl-dipeptidase activity, liberating C-terminal dipeptides
• activated by Mn+2 or Ca+2
• cleaves between Lys16 & Leu17 of beta-amyloid (A4)

Structure

• dimer of a heavy chain & a light chain cross-linked by a disulfide bond
• belongs to the peptidase C1 family

Compartment

lysosome, melanosome

Pathology

implicated in tumor invasion & metastasis

More general terms

• cysteine proteinase; thiol proteinase
• cathepsin
• APP alpha-secretase

Additional terms

• amyloid precursor protein; A4/beta amyloid precursor protein (APP)
• APP secretase

Database

• UniProt: http://www.uniprot.org/uniprot/P07858.html
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1508
• OMIM: https://mirror.omim.org/entry/116810
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=1508