Fam20A golgi-associated secretory pathway pseudokinase (Fam20A)

Fam20A is a secretory pathway pseudokinase that allosterically activates the Golgi casein kinase Fam20C, facilitating phosphorylation of numerous secreted proteins important for biomineralization and extracellular matrix function[1][2][4]. Unlike canonical kinases, Fam20A lacks a critical active site residue and cannot catalyze phosphorylation itself; instead, it binds ATP in a unique inverted conformation and forms heterodimeric/tetrameric complexes with Fam20C to enhance its kinase activity[1][2][3]. Fam20A is crucial for proper enamel formation, with inactivating mutations causing amelogenesis imperfecta and enamel-renal syndrome (characterized by abnormal enamel and renal calcification)[2][3][4]. It is expressed predominantly in vertebrate enamel tissues and lactating mammary glands[2]. Fam20A belongs to the Fam20 kinase family, which also includes Fam20C and Fam20B—each with distinct substrate specificity and regulatory mechanisms[1][2]. Fam20A is not a direct drug target; therapeutic interest centers on its interaction with Fam20C and its potential as a genetic biomarker in dental and renal diseases[1][2][4].

Other names

Family with sequence similarity 20 member AEnamel-renal syndrome proteinAmelogenesis imperfecta protein (occasionally used in clinical genetics)Pseudokinase FAM20A

Allosteric modulation of Fam20C kinase function via Fam20A binding; would control secretory pathway phosphorylation by modulating Fam20C activity[1][2][3][4]