The heterotrimeric GTP binding proteins, which consist of, β, and subunits function to transmit information from cell surface receptors to intracellular effectors. The a-subunit proteins are important because it bind and hydrolyze GTP. Lithium inhibits the function of subunits by decreasing the affinity with which they bind GTP. Recent results implicate roles for the human -subunit of the olfactory G-protein (G -olf, 18p11) (Berrettini et al., 1995) and G-protein -subunit gene (GNAZ, 22q11) for bipolar disorder I (BPI) (Saito et al., 1999). Our hypothesis is that levels of G -olf in BPI subjects are altered, and lithium treatment modulates levels of G -olf protein. We cultured lymphoblastoid cell lines derived from ten unaffected and ten bipolar subjects. Mem-brane-soluble proteins were analyzed by PAGE and western immunoblotting using two antibodies: i) anti G -olf IgG raised against amino acids 100-118 within Ga-olf and ii) anti G -z IgG raised against amino acids 93-112 within G -z. We detected G -olf as ∼46 kDa protein bands when anti G -olf or anti G -z was used to probe western immunoblots. We used anti-HSP antibody (72 kDa protein band) as an internal control. To determine relative levels of Ga-olf in different subjects, we used signal ratio of G -olf to HSP-72. Our results suggest that each subject falls into one of three categories. First, 'Low G -olf, Li-insensitive' group showed low to moderate G -olf levels that were unchanged with lithium. Second, 'High G -olf, Li-insensitive' group displayed high G -olf levels that were unchanged with lithium. Third, 'High G -olf, Li-sensitive' group showed high G -olf protein levels that were changed with lithium treatment. In our samples, levels of G -olf protein are independent of affected status of the subjects. These results demonstrate that lymphoblastoid cell lines from subjects are useful to determine levels of proteins from G -olf and GNAZ genes. We thank Ms. Z. Zhu, C. Smiley, and Indiana Division of Mental Health and CIMR (cell lines).
|Original language||English (US)|
|Number of pages||1|
|Journal||American Journal of Medical Genetics - Neuropsychiatric Genetics|
|State||Published - Aug 7 2000|
ASJC Scopus subject areas
- Psychiatry and Mental health
- Cellular and Molecular Neuroscience