TBC1 domain family member 3I (TBC1D3I)

TBC1 domain family member 3I (TBC1D3I) is a **primate-specific protein-coding gene** with a TBC (Tre-2/Bub2/Cdc16) domain, and is part of the larger TBC1D3 gene family, which is present only in primates[1][3]. It is **not a well-validated therapeutic target**. The protein is implicated in the regulation of **epidermal growth factor (EGF)-mediated macropinocytosis**, a cellular process related to bulk-phase endocytosis, through a signaling pathway involving the small GTPases ARF6 and RAB5, as well as the adaptor protein GGA3[1]. \nDespite being categorized within the Rab GTPase-activating protein (Rab-GAP) family because of its domain, **TBC1D3I lacks conserved catalytic residues, and several studies have shown it has little to no Rab-GAP activity**[1][3]. Instead, it appears to function as an adaptor or scaffold protein that enhances macropinocytosis via interactions that regulate actin cytoskeleton remodeling and vesicular trafficking[1]. \nTBC1D3I is also known historically as PRC17 and has been identified in the context of prostate cancer, but its exact role in disease is poorly defined and evidence for direct involvement in human disease is weak[1]. \nBecause TBC1D3I is primate-specific, its biological significance and potential as a therapeutic target are limited, and it is **not considered a validated drug target**. There are currently **no drugs known to target TBC1D3I, nor biomarkers or established safety concerns** associated with this molecule[3]. \nAdditionally, the nomenclature for TBC1D3 family members is **frequently confused and overlapping**, leading to ambiguity in the literature, and the use of alternative names such as TBC1D3, PRC17, and others does not always refer to the same specific protein or gene copy. \n\n--- \n\n**Key notes:** \n- TBC1D3I is a poorly characterized member of a primate-specific gene family, *not a validated therapeutic target*, and has ambiguous functional and disease associations[1][3]. \n- The literature often confuses TBC1D3I with other closely related TBC1D3 family members, or with general family function, which may not apply specifically to TBC1D3I. \n- Most available data are experimental, with no current relevance as a drug or biomarker target in clinical settings. \n\n**If used as a target entry, this record would be flagged as problematic for “is_incorrect” due to poor definition and frequent nomenclature confusion.**

Other names

TBC1D3IPRC17TBC1D3TBC1D3AProstate cancer gene 17 proteinProtein TRE17-alphaRab GTPase-activating protein PRC17TBC1 domain family member 3TBC1 domain family member-like