The Kluyveromyces Lactis Equivalent of Casein Kinase I Is Required for the Transcription of the Gene Encoding the Low-Affinity Glucose Permease

Mol Gen Genet. 1997 Jan 27;253(4):469-77. doi: 10.1007/s004380050345.


The RAG8 gene of Kluyveromyces lactis, which is one of the genes controlling the expression of the low-affinity carrier gene RAG1, has been cloned by in vivo complementation of the rag8 mutation. The sequence of Rag8p (535 amino acids), deduced from the nucleotide sequence of the cloned RAG8 gene, has been found to share a high degree of identity with the two casein kinases I of Saccharomyces cerevisiae, Yck1p and Yck2p, encoded by YCK1 and YCK2: the proteins are 65-66%, identical overall and show 89-90% identity in the kinase domain. The finding that the RAG8 gene of K. lactis cloned in a centromeric vector was able to complement the growth defect of a yck1 delta yck2(ts) mutant of S. cerevisiae strongly suggested that Rag8p is a casein kinase I. In contrast to the S. cerevisiae homologs, the RAG8 gene of K. lactis seems to be an essential single-copy gene, as shown by Southern blot experiments and the lethality of the rag8 null mutation. Northern blot analysis showed that the transcription of the RAG8 gene was higher on glucose media than in cells grown on a non-fermentable carbon source.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Biological Transport
  • Casein Kinase I*
  • Casein Kinases
  • Gene Expression Regulation, Fungal*
  • Genes, Fungal*
  • Genetic Complementation Test
  • Glucose / metabolism
  • Kluyveromyces / enzymology
  • Kluyveromyces / genetics*
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Phosphoenolpyruvate Sugar Phosphotransferase System / genetics*
  • Protein Kinases / chemistry
  • Protein Kinases / genetics*
  • Protein Kinases / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Transcription, Genetic


  • Saccharomyces cerevisiae Proteins
  • Protein Kinases
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • phosphoenolpyruvate-glucose phosphotransferase
  • Casein Kinase I
  • Casein Kinases
  • YCK1 protein, S cerevisiae
  • YCK2 protein, S cerevisiae
  • Glucose

Associated data

  • GENBANK/X79769