AMFR

AMFR Full Name

autocrine motility factor receptor, E3 ubiquitin protein ligase

AMFR Introduction

AMFR, located on chromosome 16q13, encodes a glycosylated transmembrane receptor that uniquely combines two distinct functional domains within a single protein. On the cell surface, AMFR serves as the receptor for autocrine motility factor (AMF), a tumor-derived secreted protein that stimulates random and directed cell migration, a property exploited by malignant cells during invasion and metastasis. Concurrently, the intracellular domain of AMFR functions as a RING-type E3 ubiquitin ligase (also referred to as GP78 or RNF45), catalyzing the covalent attachment of ubiquitin molecules to specific substrate proteins and targeting them for proteasomal degradation through the endoplasmic reticulum-associated degradation (ERAD) pathway. This dual functionality allows AMFR to simultaneously regulate cell motility signaling and protein quality control. Its E3 ligase activity extends to a growing list of physiological substrates, including Insig1 in cholesterol metabolism, TMCO1 in calcium homeostasis, and key regulators of the Wnt, NF-κB, and SREBP signaling cascades.

Figure 1. Overview of structure, functions and regulations of AMFR/Gp78. (Source: Joshi V, et al. 2017)

Within neurons, AMFR exhibits a polarized subcellular distribution, localizing to the endoplasmic reticulum membrane in dendritic shafts, growth cones, and neuronal cell bodies, where it supports axonal maintenance and synaptic integrity. Importantly, biallelic loss-of-function mutations in AMFR cause autosomal recessive spastic paraplegia type 89 (SPG89), a hereditary neurodegenerative disorder characterized by progressive lower limb spasticity, developmental delay, and motor impairment. A landmark 2023 study demonstrated that statin treatment can rescue the neurological phenotype in AMFR-deficient preclinical models, opening a promising therapeutic avenue for this otherwise untreatable condition. Beyond neurodegeneration, AMFR is frequently overexpressed in epithelial malignancies including prostate, breast, and lung carcinomas, where it promotes tumor cell proliferation, motility, and metastatic spread, rendering it a potential dual-purpose biomarker for both neurological and oncological applications.

Alternate Names for AMFR

AMFR; autocrine motility factor receptor; gp78; RNF45; isoform 2; AMF receptor; AMF receptor isoform 1; AMF receptor isoform 2; AMFR; AMFR2_HUMAN; Autocrine motility factor receptor; Autocrine motility factor receptor precursor, isoform 1; Autocrine motil

• 1. Joshi V, et al. Gp78 E3 Ubiquitin Ligase: Essential Functions and Contributions in Proteostasis. Front Cell Neurosci. 2017 Aug 25;11:259.
  2. Deng R,et al. AMFR dysfunction causes autosomal recessive spastic paraplegia in human that is amenable to statin treatment in a preclinical model. Acta Neuropathol. 2023 Aug;146(2):353-368.