Related Experiment Videos
Recombinant SEC14-like proteins (TAP) possess GTPase activity
Daniel Habermehl1, Petra Kempna, Angelo Azzi
1Institute of Biochemistry and Molecular Biology, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.
Biochemical and Biophysical Research Communications
|November 30, 2004
Summary
Three human SEC14-like proteins (TAP1-3) bind lipids and show GTPase activity. Their structure suggests a novel active site for GTP binding and hydrolysis, distinct from typical G-protein domains.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Science
Background:
- SEC14-like proteins are involved in lipid transport.
- The specific functions and structural characteristics of human TAP proteins (TAP1, TAP2, TAP3) remain incompletely understood.
- Understanding these proteins is crucial for insights into cellular lipid metabolism and signaling.
Purpose of the Study:
- To characterize the biochemical properties of recombinant human TAP1, TAP2, and TAP3 proteins.
- To investigate the ligand-binding capabilities of TAP proteins.
- To explore the GTPase activity and structural basis for potential GTP binding in TAP proteins.
Main Methods:
- Expression and purification of recombinant TAP1, TAP2, and TAP3 proteins using an amino-terminal His-tag in Escherichia coli.
- Ligand-binding assays to assess interactions with tocopherols, phospholipids, and squalene.
- GTPase activity assays to quantify enzymatic function.
- Structural analysis to identify conserved GTPase motifs and their spatial arrangement.
Main Results:
- Recombinant TAP proteins were successfully purified.
- TAP proteins demonstrated binding affinity for alpha-, beta-, gamma-, and delta-tocopherol, specific phospholipids, and squalene.
- Significant GTPase activity was observed, comparable to Rab family GTP-binding proteins.
- While containing canonical GTPase motifs, the surrounding secondary structure of TAP proteins differed from typical G-protein domains, yet these motifs were spatially proximate, suggesting a functional active site.
Conclusions:
- Human TAP proteins possess lipid-binding capabilities and exhibit GTPase activity.
- The unique structural arrangement of GTP-binding motifs in TAP proteins suggests a novel mechanism for GTP binding and hydrolysis.
- These findings expand our understanding of SEC14-like protein function and their potential roles in cellular processes involving lipid and GTP metabolism.