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The L6 membrane proteins--a new four-transmembrane superfamily
1The Walter and Eliza Hall Institute of Medical Research, Post Office Royal Melbourne Hospital, Victoria, Australia. wright_m@wehi.edu.au
Protein Science : a Publication of the Protein Society
|September 7, 2000
Summary
Four cell surface proteins, including L6 and TM4SF5, were previously classified as tetraspanins. New analysis reveals they form their own distinct L6 superfamily, not related to tetraspanins.
Area of Science:
- Molecular Biology
- Cell Biology
- Protein Classification
Background:
- L6, IL-TMP, and TM4SF5 are cell surface proteins with four predicted transmembrane domains.
- Previous studies assigned these proteins to the tetraspanin superfamily based on sequence analysis.
Purpose of the Study:
- To re-evaluate the classification of L6, IL-TMP, and TM4SF5.
- To investigate the relationship between these proteins and the tetraspanin superfamily.
- To identify and characterize a newly discovered related sequence, L6D.
Main Methods:
- Comparative sequence analysis of L6, IL-TMP, TM4SF5, and the newly identified L6D sequence.
- Bioinformatic analysis to assess evolutionary relationships and structural similarities.
Main Results:
- A new sequence, L6D, was identified with high similarity to L6, IL-TMP, and TM4SF5.
- Sequence analyses demonstrated that L6, IL-TMP, TM4SF5, and L6D are not significantly related to known tetraspanins.
- These four proteins represent a distinct protein family, proposed as the L6 superfamily.
Conclusions:
- The classification of L6, IL-TMP, and TM4SF5 as tetraspanins is inaccurate.
- A new protein superfamily, the L6 superfamily, has been identified.
- This finding necessitates a reclassification of these cell surface proteins.