Toh KL, Jones CR, He Y, Eide EJ, Hinz WA, Virshup DM, Ptácek LJ, Fu YH. Science. 2001 Feb 9;291(5506):1040-3.
The purpose of this study was to determine the genetic and biochemical basis for Familial Advanced Sleep Phase (FASPS) Syndrome. The authors mapped the gene to the qter region of Chromosome 2 via linkage analysis confirmed by PCR. One gene in this region is the human homolog of the Drosophila period gene (as confirmed by bacterial artificial cloning and mapping), mutations of which lead to abberant circadian rhythms.
An S662G mutation was indentified in this region via Single-strand conformation polymorphism. Many of the sampled individuals diagnosed with FASPS while none of the controls had this mutation.
This mutation was then characterized by several experiments. It was found that the mutation occured within the Casein Kinase 1 Epsilon (CSNK1E) binding domain by immunoprecipitation, and the mutated site is a phosphorylation target by electrophoresis. Additionally, the mutated site is C-terminal to many other phosphorylation sites by sequencing, and the authors hypothesize that it is the initiation site of a phosphorylation cascade. This hypothesis was confirmed by comparing a S662D mutant (similar to a phosphoserine) to the wildtype and S662G proteins.