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A 25 kDa alpha 2-microglobulin-related protein is a component of the 125 kDa form of human gelatinase
S Triebel1, J Bläser, H Reinke
1Department of Biochemistry, Faculty of Chemistry, University of Bielefeld, Germany.
Abstract:
Besides the monomeric mammalian 95 kDa progelatinase, two additional forms, a disulfide-bridged 220 kDa dimer and a 125 kDa form were isolated from human PMN leukocytes. The 125 kDa progelatinase was identified as a covalently linked, disulfide-bridged heterodimer formed of the monomer with a 25 kDa protein. This 25 kDa protein was isolated from gelatinase bound to the affinity support of gelatin-Sepharose and eluted by DTE-containing buffer. The amino acid sequence of tryptic peptides of this protein revealed homology with an alpha 2-microglobulin-related protein from rats, a protein so far unknown in humans.
Insights
Researchers identified novel forms of progelatinase in human leukocytes, including a 125 kDa form. This form is a heterodimer linked to a previously unknown human protein homologous to rat alpha 2-microglobulin.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Progelatinase, a key enzyme in extracellular matrix degradation, exists in various forms.
- Human polymorphonuclear (PMN) leukocytes are a source of matrix metalloproteinases, including gelatinases.
Purpose of the Study:
- To characterize novel forms of progelatinase isolated from human PMN leukocytes.
- To identify the protein component of a newly discovered 125 kDa progelatinase complex.
Main Methods:
- Isolation and purification of progelatinase forms from human PMN leukocytes.
- Affinity chromatography using gelatin-Sepharose.
- Peptide sequencing and homology analysis.
Main Results:
- Three progelatinase forms were isolated: 95 kDa monomer, 220 kDa dimer, and 125 kDa form.
- The 125 kDa form is a disulfide-bridged heterodimer of monomeric progelatinase and a 25 kDa protein.
- The 25 kDa protein showed homology to rat alpha 2-microglobulin, a protein previously unknown in humans.
Conclusions:
- Human PMN leukocytes contain complex forms of progelatinase.
- A novel 25 kDa protein, homologous to rat alpha 2-microglobulin, is associated with human progelatinase.
- This discovery expands the known repertoire of proteins interacting with gelatinase in humans.