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cDNA sequence and mRNA tissue distribution of a novel human matrix metalloproteinase with a potential transmembrane
1InViTek GmbH, Berlin-Buch, Germany.
Abstract:
The complementary DNA sequence of a novel matrix metalloproteinase was isolated from a human lung cDNA library. It consists of 3530 bp and encodes a polypeptide of 669 amino acids. In comparison to other matrix metalloproteinases, the deduced sequence of the amino acid chain exhibits closest similarity to a recently discovered membrane-type matrix metalloproteinase of 582 amino acids. Likewise, it is composed of a signal peptide, a prodomain, a catalytic domain, a hemopexin-homologous domain and a C-terminal domain. Furthermore, the novel matrix metalloproteinase shares a similar activation site with its 582-amino-acid homologue, an insertion of eight amino acids in the catalytic domain and a tract of more than 20 hydrophobic amino acids near the C-terminus. The hydrophobic structure in the C-terminal domain suggests that the novel matrix metalloproteinase is also membrane bound. When lung cell membrane fractions were probed in immunoblots with polyclonal antibodies against a recombinant fragment of the 669-amino-acid chain, a protein of M(r) 72,000 reacted preferentially with the antibodies. Northern-blot analysis demonstrated quite different tissue distributions of mRNA for the two membrane-type matrix metalloproteinases. While mRNA for the 582-amino-acid enzyme was found predominantly in lung, placenta, kidney, ovary, intestine, prostate and spleen, mRNA for the 669-amino-acid enzyme appeared to be synthesized preferentially in liver, placenta, testis, colon and intestine. Substantial amounts of the latter mRNA were also detected in pancreas, kidney, lung, heart and skeletal muscle.
Insights
Researchers identified a new human matrix metalloproteinase (MMP) with a unique sequence and tissue distribution. This membrane-bound MMP, distinct from known variants, shows preferential expression in liver and placenta.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Matrix metalloproteinases (MMPs) are crucial enzymes involved in extracellular matrix remodeling.
- Membrane-type MMPs (MT-MMPs) play significant roles in various physiological and pathological processes.
- Understanding novel MMPs is vital for deciphering their functions and therapeutic potential.
Purpose of the Study:
- To isolate and characterize a novel human matrix metalloproteinase from a lung cDNA library.
- To determine the structural and functional similarities and differences with known MMPs.
- To investigate the tissue-specific expression pattern of the newly identified MMP.
Main Methods:
- Complementary DNA (cDNA) sequencing and analysis.
- Amino acid sequence comparison with known MMPs.
- Immunoblotting using polyclonal antibodies against a recombinant protein fragment.
- Northern-blot analysis for mRNA tissue distribution.
Main Results:
- A novel human MMP cDNA sequence of 3530 bp was isolated, encoding a 669-amino acid polypeptide.
- The deduced amino acid sequence showed closest similarity to a known 582-amino acid membrane-type MMP, sharing structural domains and an activation site.
- Hydrophobic C-terminal domain suggested membrane-bound localization; immunoblotting confirmed a 72,000 M(r) protein in lung cell membranes.
- Northern blot analysis revealed distinct tissue expression patterns, with the novel MMP mRNA predominantly found in liver, placenta, testis, colon, and intestine.
Conclusions:
- A novel membrane-bound matrix metalloproteinase has been identified and characterized.
- This new MMP exhibits a unique tissue expression profile compared to a previously identified homologue.
- Further research into this novel MMP may elucidate its specific roles in human physiology and disease.