Growth hormone regulated TBC protein 1 (GRTP1) was identified through microarray analysis as a gene whose expression is regulated by growth hormone (GH). It contains the TBC signature motif of GTPase activator proteins of Rab-like small GTPases. GRTP1 mRNA is expressed at highest levels in testes, and is also present in kidney, lung, liver, and intestine. Administration of GH to mice resulted in an increase in GRTP1 mRNA in testes, but a decrease of GRTP1 mRNA in kidney and liver (1). GRTP1 was identified as an HIV dependency factor (HDF), suggesting that GRTP1 may be an important drug target in HIV treatment.Synonyms: Growth hormone-regulated TBC protein 1, TBC1 domain family member 6