The present invention relates to nucleotide sequences that encode and may be used to express amino acid sequences that are useful in the identification and development of compounds with activity as pharmaceuticals, in particular of compounds for the prevention and treatment of metabolic diseases such as diabetes and obesity. The invention also relates to the amino acid sequences--such as proteins and polypeptides--that are encoded by, and that may be obtained by suitable expression of, the nucleotide sequences of the invention, particularly the amino acid sequences of JIK, PSK, TAO1 and Q9P2I6. The invention also relates to various uses and modulators of, and methods incorporating, the nucleotide and amino acid sequences of the invention.