The enzymatic activity of ADAM8 and ADAM9 is not regulated by TIMPs.
The ADAM family of proteases are type I transmembrane proteins with both metalloproteinase and disintegrin containing extracellular domains. ADAMs are implicated in the proteolytic processing of membrane-bound precursors and involved in modulating cell-cell and cell-matrix interactions. ADAM8 (MS2, CD156) has been identified in myeloid and B cells. In this report we demonstrate that soluble ADAM8 is an active metalloprotease in vitro and is able to hydrolyse myelin basic protein and a variety of peptide substrates based on the cleavage sites of membrane-bound cytokines, growth factors and receptors which are known to be processed by metalloproteinases. Interestingly, although ADAM8 was inhibited by a number of peptide analogue hydroxamate inhibitors, it was not inhibited by the tissue inhibitors of metalloproteinases (TIMPs). We also demonstrate that the activity of recombinant soluble ADAM9 (meltrin-gamma, MDC9) lacks inhibition by the TIMPs, but can be inhibited by hydroxamate inhibitors. The lack of TIMP inhibition of ADAM8 and 9 contrasts with other membrane-associated metalloproteinases characterised to date in this respect (ADAM10, 12, 17, and the membrane-type metalloproteinases) which have been implicated in protein processing at the cell surface.
School of Biological Sciences, University of East Anglia, Norwich, UK.
Augustin
A
Amour
C Graham
CG
Knight
William R
WR
English
Ailsa
A
Webster
Patrick M
PM
Slocombe
Vera
V
Knäuper
Andrew J P
AJ
Docherty
J David
JD
Becherer
Carl P
CP
Blobel
Gillian
G
Murphy
D051722:ADAM Proteins; D000595:Amino Acid Sequence; D015703:Antigens, CD; D000954:Antigens, Surface / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002384:Catalysis; D002846:Chromatography, Affinity; D019483:Disintegrins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*
D015703:Antigens, CD; D000954:Antigens, Surface; D019483:Disintegrins; D008565:Membrane Proteins; D011994:Recombinant Proteins; D019714:Tissue Inhibitor of Metalloproteinases; D051722:ADAM Proteins; C098339:ADAM9 protein, human; D008666:Metalloendopeptidases