Abstract
A novel 913-amino acid protein, gamma-aminobutyric acid type A (GABA(A)) receptor interacting factor-1 (GRIF-1), has been cloned and identified as a GABA(A) receptor-associated protein by virtue of its specific interaction with the GABA(A) receptor beta 2 subunit intracellular loop in a yeast two-hybrid assay. GRIF-1 has no homology with proteins of known function, but it is the rat orthologue of the human ALS2CR3/KIAA0549 gene. GRIF-1 is expressed as two alternative splice forms, GRIF-1a and a C-terminally truncated form, GRIF-1b. GRIF-1 mRNA has a wide distribution with a major transcript size of 6.2 kb. GRIF-1a protein is only expressed in excitable tissues, i.e. brain, heart, and skeletal muscle major immunoreactive bands of M(r) approximately 115 and 106 kDa and, in muscle and heart only, an additional 88-kDa species. When expressed in human embryonic kidney 293 cells, GRIF-1a yielded three immunoreactive bands with M(r) approximately 115, 106, and 98 kDa. Co-expression of GRIF-1a and alpha 1 beta 2 gamma 2 GABA(A) receptors in mammalian cells revealed some co-localization in the cell cytoplasm. Anti-FLAG-agarose specifically precipitated GRIF-1(FLAG) and GABA(A) receptor beta 2 subunits from human embryonic kidney 293 cells co-transfected with GRIF-1a(FLAG) and beta 2 subunit clones. Further, immobilized GRIF-1-(8-633) specifically precipitated in vitro GABA(A) receptor alpha 1 and beta 2 subunit immunoreactivities from detergent extracts of adult rat brain. The respective GABA(A) receptor beta 2 subunit/GRIF-1 binding domains were mapped using the yeast two-hybrid reporter gene assays. A possible role for GRIF-1 as a GABA(A) receptor beta 2 subunit trafficking factor is proposed.
Highlights
The nucleotide sequence(s) reported in this paper has been submitted to the DDBJ/GenBankTM/EBI Data Bank with accession number(s) AJ288898
GRIF-1 has no homology with proteins of known function, but it is the rat orthologue of the human ALS2CR3/KIAA0549 gene
GRIF-1a protein is only expressed in excitable tissues, i.e. brain, heart, and skeletal muscle major immunoreactive bands of Mr ϳ 115 and 106 kDa and, in muscle and heart only, an additional 88-kDa species
Summary
The nucleotide sequence(s) reported in this paper has been submitted to the DDBJ/GenBankTM/EBI Data Bank with accession number(s) AJ288898. GABAA receptor-associated ubiquitin-like protein that binds the ␣1 subunit and plays a role in the stabilization of cell surface receptors [14, 15]. Using the GABAA receptor 2 intracellular loop (2-IL) as a bait, we have discovered a novel protein GABAA receptor interacting factor (GRIF-1) that is expressed predominantly in excitable tissues. The characterization of this protein is reported in this paper
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
