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The 12-transmembrane helix transporters
1Department of Biochemistry and Molecular Biology, University of Leeds, UK.
Current Opinion in Cell Biology
|August 1, 1993
Summary
Many transport proteins are thought to have 12 transmembrane alpha-helices. However, genetic and biochemical evidence for this structure and its transport mechanism is limited, with examples of both divergent and convergent evolution observed.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Many transport proteins are hypothesized to possess a 12-transmembrane alpha-helix structure based on hydropathic profiles.
- Direct genetic or biochemical evidence supporting this 12-helix model and elucidating transport mechanisms remains scarce for most proteins.
Purpose of the Study:
- To review the evidence for the 12-transmembrane alpha-helix model in transport proteins.
- To explore the evolutionary origins of transport protein structures.
Main Methods:
- Analysis of amino acid sequences and hydropathic profiles.
- Review of existing genetic and biochemical data.
- Examination of evolutionary relationships between transport protein families.
Main Results:
- Limited genetic and biochemical evidence currently supports the 12-helix model for many transport proteins.
- Observed evolutionary patterns include divergent evolution within related families and convergent evolution among distinct protein groups.
Conclusions:
- The 12-transmembrane alpha-helix model is a common hypothesis but lacks broad empirical support.
- Transport protein evolution exhibits both divergence from common ancestors and convergence from independent origins.