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10:37
Comparing the Affinity of GTPase-binding Proteins using Competition Assays
Published on: October 8, 2015
GTP binding by class II transactivator: role in nuclear import.
J A Harton1, D E Cressman, K C Chin
1Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA.
Science (New York, N.Y.)
|August 28, 1999
Summary
Class II transactivator (CIITA) binds guanosine triphosphate (GTP), a function crucial for its role in human leukocyte antigen-D (HLA-D) gene activation. This GTP binding facilitates CIITA
Area of Science:
- Molecular Biology
- Immunogenetics
- Transcriptional Regulation
Background:
- Class II transactivator (CIITA) is a key coactivator for human leukocyte antigen-D (HLA-D) genes.
- CIITA possesses motifs resembling those in guanosine triphosphate (GTP)-binding proteins.
Purpose of the Study:
- To investigate the GTP-binding capabilities of CIITA.
- To determine the functional significance of CIITA's GTP-binding motifs in transcriptional activation and nuclear import.
Main Methods:
- Site-directed mutagenesis of CIITA's putative GTP-binding motifs.
- Guanosine triphosphate (GTP) binding assays.
- Transcriptional activity assays.
- Analysis of CIITA nuclear import.
Main Results:
- CIITA directly binds guanosine triphosphate (GTP).
- Mutations in the GTP-binding motifs impair both GTP binding and transactivation.
- Substitution with analogous Ras sequences rescues CIITA function.
- GTP binding correlates with CIITA nuclear import, while enhanced GTPase activity reduces transcriptional function.
Conclusions:
- CIITA utilizes GTP binding for its nuclear import, a mechanism distinct from canonical GTP-binding proteins.
- GTP binding is essential for CIITA's role in regulating human leukocyte antigen-D (HLA-D) gene expression.
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