SET binding factor 1 (SBF1)

SET binding factor 1 (SBF1) is a large, multidomain protein encoded by the SBF1 gene located on chromosome 22q13.33, and is also known as myotubularin-related protein 5 (MTMR5)[1][2][4]. SBF1 is a member of the myotubularin family, characterized as a catalytically inactive protein tyrosine phosphatase due to missing key residues in its active site[1][6]. It has a guanine nucleotide exchange factor (GEF) domain, enabling it to activate small Rab GTPases, notably RAB28, which are involved in endolysosomal trafficking[1]. SBF1 acts as an adapter protein for the active phosphatase MTMR2, regulating its localization and function—key for processes such as autophagy and Schwann cell myelination[1]. SBF1 is predominantly expressed in the brain and skeletal muscle; its dysregulation or mutation is associated with disorders such as Charcot-Marie-Tooth disease type 4B3 (CMT4B3) and possibly late-onset neurocognitive disorders including Alzheimer’s disease[1][2][4]. SBF1 is not an established therapeutic target for any approved drugs and has no known drug interactions[1][3].

Other names

Myotubularin-related protein 5MTMR5DENND7AInactive phosphatidylinositol 3-phosphatase 5DENN/MADD domain containing 7ACMT4B3