High impact information on GIMAP4

• Despite these divergent amino acids at positions involved in GTP/guanosine diphosphate (GDP) binding and guanosine triphosphatase (GTPase) activities, we found that hIAN1 specifically binds GDP (K(d) = 0.47 microM) and GTP (K(d) = 6 microM) and exhibits intrinsic GTPase activity [1].
• Among mature hematopoietic cells, hIAN1 is specifically expressed in resting T and B lymphocytes, and its expression level tremendously decreased at the protein but not the mRNA level during B- or T-lymphocyte activation, suggesting a specific role for this new type of GTPase during the immune response [1].
• We have cloned a complementary DNA, called Human Immune Associated Nucleotide 1 (hIAN1), whose messenger RNA (mRNA) level expression is inversely correlated to the TAL-1 mRNA level in human leukemic T-cell lines [1].
• We observed that levels of both Ian1 and Ian9 proteins are profoundly reduced in T cells from lymphopenic rats as compared with wild-type rats [2].
• The proteins hGIMAP4 and hGIMAP7 can be localized at ER and Golgi apparatus, but not in mitochondria, lysosomes and nuclei [3].

Biological context of GIMAP4

• Here we show that all eight IAN family genes encoded in a single cluster of mouse genome are predominantly expressed in lymphocytes, and that the expression of IAN1, IAN4, and IAN5 is significantly elevated upon thymic selection of T lymphocytes [4].

Other interactions of GIMAP4

• Gain-of-function experiments show that the premature overexpression of IAN1 kills immature thymocytes, whereas short hairpin RNA-mediated loss-of-function studies show that IAN4 supports positive selection [4].

References