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Inter-species sequence conservation of single-spanning transmembrane regions
1Biomolecular Modelling Laboratory, Imperial Cancer Research Fund, London, UK.
Protein Engineering
|October 1, 1990
Summary
Integral membrane protein transmembrane regions show significant sequence identity across species, suggesting functional constraints beyond simple membrane passage. Low identity in specific regions may indicate they do not interact with other transmembrane sections.
Area of Science:
- Molecular Biology
- Biophysics
- Protein Science
Background:
- Integral membrane proteins are crucial for cellular functions.
- Transmembrane regions (TMRs) anchor proteins within the lipid bilayer.
- Understanding TMR sequence conservation provides insights into protein structure and function.
Purpose of the Study:
- To evaluate inter-species sequence identity in single-spanning TMRs of integral membrane proteins.
- To compare sequence identity between homologous and unrelated TMRs.
- To infer functional and structural constraints on TMRs.
Main Methods:
- Comparative sequence analysis of human and rodent TMRs.
- Calculation of sequence identity percentages for homologous TMRs.
- Comparison of identity values between homologous and unrelated TMRs.
Main Results:
- Homologous human and rodent TMRs exhibit identity ranging from 32% to 100%.
- Mean identity for homologous TMRs (e.g., 14% for unrelated sections) is higher than for other protein regions.
- Three TMRs (CD2, MHC class I, ICAM-1) showed <50% identity, suggesting limited inter-transmembrane interactions.
Conclusions:
- TMRs are under structural and/or functional constraints.
- Sequence conservation in TMRs exceeds that expected for passive membrane anchors.
- Low inter-species identity in specific TMRs may correlate with a lack of interaction with other transmembrane sections.