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Cloning and expression of a divergent integrin subunit beta 8
M Moyle1, M A Napier, J W McLean
1Department of Cardiovascular Research, Genentech, Inc., South San Francisco, California 94080.
The Journal of Biological Chemistry
|October 15, 1991
Summary
Researchers identified a novel integrin beta 8 subunit in rabbits and humans. This new subunit exhibits unique structural features and can complex with the alpha v subunit, forming a cell surface integrin.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Integrins are crucial cell surface receptors involved in cell adhesion and signaling.
- The diversity of integrin subunits allows for a wide range of functional specificities.
- Identification of novel subunits expands our understanding of the integrin repertoire.
Purpose of the Study:
- To identify and characterize a novel integrin beta subunit, designated beta 8.
- To investigate the structural features and evolutionary conservation of the beta 8 subunit.
- To determine the expression pattern and potential function of the beta 8 integrin.
Main Methods:
- Isolation of rabbit and human cDNA clones encoding the beta 8 subunit using oligonucleotide probes and library screening.
- Sequence analysis to determine amino acid identity, domain structure, and unique features compared to other beta subunits.
- Northern blot and PCR analysis to assess beta 8 mRNA expression in various tissues and cell lines.
- Transient expression in 293 cells and co-immunoprecipitation to study complex formation with alpha v subunit.
Main Results:
- Novel integrin beta 8 subunit identified in rabbit and human cDNA libraries.
- Beta 8 subunit shows high inter-species conservation (approx. 90% identity) but distinct amino acid identity (31-37%) with other beta subunits (beta 1-7).
- Unique structural features include absence of specific cysteine residues and a non-homologous cytoplasmic domain.
- Beta 8 mRNA is expressed in rabbit placenta, kidney, brain, ovary, uterus, and human transformed cell lines.
- Transiently expressed beta 8 subunit complexes with endogenous alpha v subunit in 293 cells, forming a cell surface integrin.
Conclusions:
- The integrin beta 8 subunit represents a distinct member of the integrin beta family with unique structural characteristics.
- The expression pattern suggests diverse roles in various physiological processes.
- The ability of beta 8 to complex with alpha v indicates its functional integration into the cell surface integrin system.