The invention provides an isolated gene encoding Mch4 or an isolated gene
encoding Mch5 as well as functional fragments thereof. Also provided are
isolated nucleic acid sequences encoding Mch4 or Mch5 or functional
fragment thereof. The gene or nucleic acid sequences can be single or
double stranded nucleic acids corresponding to coding or non-coding
strands of the Mch4 or Mch5 nucleotide sequences. Isolated Mch4 or Mch5
polypeptides or functional fragments thereof are also provided.