Synthesis of monohydroxylated inositolphosphorylceramide (IPC-C) in Saccharomyces cerevisiae requires Scs7p, a protein with both a cytochrome b5-like domain and a hydroxylase/desaturase domain

Yeast. 1998 Mar 15;14(4):311-21. doi: 10.1002/(SICI)1097-0061(19980315)14:4<311::AID-YEA220>3.0.CO;2-B.

Abstract

Saccharomyces cerevisiae mutants lacking Scs7p fail to accumulate the inositolphosphorylceramide (IPC) species. IPC-C, which is the predominant form found in wild-type cells. Instead scs7 mutants accumulate an IPC-B species believed to be unhydroxylated on the amide-linked C26-fatty acid. Elimination of the SCS7 gene suppresses the Ca(2+)-sensitive phenotype of csg1 and csg2 mutants. The CSG1 and CSG2 genes are required for mannosylation of IPC-C and accumulation of IPC-C by the csg mutants renders them Ca(2+)-sensitive. The SCS7 gene encodes a protein that contains both a cytochrome b5-like domain and a domain that resembles the family of cytochrome b5-dependent enzymes that use iron and oxygen to catalyse desaturation or hydroxylation of fatty acids and sterols. Scs7p is therefore likely to be the enzyme that hydroxylates the C26-fatty acid of IPC-C.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Calcium / metabolism
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Chromosome Mapping
  • Cloning, Molecular
  • Cytochrome b Group / chemistry*
  • Genes, Fungal
  • Hydroxylation
  • Mixed Function Oxygenases / chemistry
  • Mixed Function Oxygenases / genetics*
  • Mixed Function Oxygenases / metabolism
  • Mutation
  • Open Reading Frames
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Sphingolipids / biosynthesis*

Substances

  • CSG2 protein, S cerevisiae
  • Calcium-Binding Proteins
  • Cytochrome b Group
  • Saccharomyces cerevisiae Proteins
  • Sphingolipids
  • Mixed Function Oxygenases
  • Scs7 protein, S cerevisiae
  • Calcium