摘要
A novel matrix metalloproteinase (MMP) was identified from leukocytes and found to be specifically expressedby peripheral blood leukocytes among 29 different tissuesexamined. Named leukolysin, it encodes for 562 residueswith a conserved MMP structure, i.e., pre-, pro-, catalytic , hinge- and hemopexin-like domains, but also a RXK/RRmotif, known for its role in MMP zymogen activation, anda C-terminal hydrophobic segment. Overall, leukolysindisplays the strongest homology to the newly identifiedMT-MMP subgroup with 45% and 39% identities to MT4and MT1-MMPs vs 30% and 31.5% to MMP1 and 3 respectively. Unlike MT4-MMP whose proteolytic activityremains undefined, a C-terminally truncated leukolysin isexpressed as a strong gelatinolytic species at 28 kDa whichis derived from a cell-associated 34 kDa proenzyme, presumably by furin or proprotein convertase mediated removal of the propeptide (-6 kDa). By green fluorescentprotein (GFP) tagging, the intracellular proenzyme is localized to granules throughout the cell, suggesting thatactivation occur immediately prior to secretion. Taken together, leukolysin may be part of the proteolytic arsenaldeployed by leukocytes during inflammatory responses.
