Fam20C represents the C-terminus of eukaryotic secreted Golgi casein kinase proteins. Fam20C is the Golgi casein kinase that phosphorylates secretory pathway proteins within Ser-x-Glu/pSer motifs. Mutations in Fam20C cause Raine syndrome, an autosomal recessive osteosclerotic bone dysplasia [1].

1: Crystal structure of the Golgi casein kinase. Xiao J, Tagliabracci VS, Wen J, Kim SA, Dixon JE; Proc Natl Acad Sci U S A. 2013;110:10574-10579. PMID:23754375