FNTB

FNTB Full Name

farnesyltransferase, CAAX box, beta

FNTB Introduction

FNTB encodes the beta subunit of protein farnesyltransferase (FTase), a heterodimeric enzyme that catalyzes the addition of a farnesyl isoprenoid lipid moiety to the cysteine residue within a carboxyl-terminal CAAX motif (where C is cysteine, A is an aliphatic amino acid, and X is any amino acid). This post-translational lipid modification, known as prenylation, is essential for the proper membrane localization and functional activation of numerous signaling proteins, most notably the Ras family of small GTPases. By anchoring farnesylated proteins to cellular membranes, FNTB-mediated prenylation enables critical signal transduction cascades that regulate cell proliferation, differentiation, and survival. The beta subunit of FTase provides the binding site for the farnesyl pyrophosphate (FPP) donor substrate and contributes to the structural integrity of the heterodimeric complex, while the alpha subunit primarily recognizes the CAAX motif of substrate proteins.

Figure 1. Prenylation of CAAX proteins. (Source: Philips MR, et al. 2007)

The pathophysiological significance of FNTB has been extensively studied in the context of oncogenesis and neurodegeneration. Because oncogenic Ras proteins require farnesylation for membrane localization and transforming activity, FTase has long been pursued as a therapeutic target in cancer, leading to the development of farnesyltransferase inhibitors (FTIs) that have shown clinical efficacy in certain malignancies. More recently, protein farnesylation has been implicated in Alzheimer's disease pathogenesis: elevated FTase expression and sustained protein farnesylation have been documented in postmortem Alzheimer's brain tissues, and neuron-specific suppression of farnesyltransferase mitigates multiple pathogenic processes in Alzheimer's disease mouse models, including amyloid-beta plaque formation, tau hyperphosphorylation, and synaptic dysfunction. These findings position FNTB as a convergent node linking lipid metabolism, oncogenic signaling, and neurodegenerative disease, with therapeutic implications spanning oncology and neurology.

Alternate Names for FNTB

FNTB; farnesyltransferase, CAAX box, beta; protein farnesyltransferase subunit beta; FTase-beta; farnesyltransferase beta subunit; CAAX farnesyltransferase subunit beta; ras proteins prenyltransferase subunit beta; MGC105303;

• 1. Philips MR, et al. Geranylgeranyltransferase I as a target for anti-cancer drugs. J Clin Invest. 2007 May;117(5):1223-5.
  2. Jeong A, et al. Protein farnesylation is upregulated in Alzheimer's human brains and neuron-specific suppression of farnesyltransferase mitigates pathogenic processes in Alzheimer's model mice. Acta Neuropathol Commun. 2021 Jul 27;9(1):129.