Geranylgeranyl transferase type-2 subunit beta

Geranylgeranyl transferase type-2 subunit beta (RABGGTB) is a catalytic subunit that transfers geranylgeranyl moieties from geranylgeranyl diphosphate to Rab proteins and other substrates with specific C-terminal cysteine motifs (UniProt: P53611). This modification is essential for proper protein localization and function. RABGGTB operates as part of the geranylgeranyl transferase type-3 complex, which geranylgeranylates Rab proteins such as RAB1A, RAB3A, RAB5A, and RAB7A, as well as non-Rab substrates like FBXL2 and the Golgi SNARE protein YKT6 (UniProt: P53611). These modifications regulate Golgi SNARE assembly and E3 ubiquitin-ligase complex function.

In Alzheimer's disease research, RABGGTB shows ambiguous regulation across subcellular fractions of post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). The mean log2 fold-change is 0.26, indicating marginal overall elevation, but direction varies by subcellular fraction in the four-fraction TMT proteomics experiment. No specific UniProt disease annotation links RABGGTB to AD pathology. Further investigation across distinct brain compartments may clarify whether altered prenylation of Rab and SNARE proteins contributes to AD-associated synaptic or vesicular transport dysfunction.