Sterol-regulated release of SREBP-2 from cell membranes requires two sequential cleavages, one within a transmembrane segment

Cell. 1996 Jun 28;85(7):1037-46. doi: 10.1016/s0092-8674(00)81304-5.

Abstract

Sterol regulatory element binding proteins (SREBPs) are transcription factors attached to the endoplasmic reticulum. The NH2-segment, which activates transcription, is connected to membranes by a hairpin anchor formed by two transmembrane sequences and a short lumenal loop. Using H-Ras-SREBP-2 fusion proteins, we show that the NH2-segment is released from membranes by two sequential cleavages. The first, regulated by sterols, occurs in the lumenal loop. The second, not regulated by sterols, occurs within the first transmembrane domain. The liberated NH2-segment enters the nucleus and activates genes controlling cholesterol synthesis and uptake. Certain mutant Chinese hamster ovary cells are auxotrophic for cholesterol because they fail to carry out the second cleavage; the NH2-segment remains membrane-bound and transcription is not activated.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • CHO Cells / cytology
  • CHO Cells / drug effects
  • CHO Cells / physiology
  • Cell Line / cytology
  • Cell Line / drug effects
  • Cell Line / physiology
  • Cholesterol / biosynthesis
  • Cholesterol / genetics
  • Cricetinae
  • DNA, Complementary / genetics
  • DNA-Binding Proteins / drug effects*
  • DNA-Binding Proteins / metabolism
  • Endopeptidases / metabolism
  • Epitopes / genetics
  • Humans
  • Immunoblotting
  • Kidney / cytology
  • Leucine Zippers / drug effects
  • Membrane Proteins / chemistry
  • Membrane Proteins / drug effects
  • Membrane Proteins / metabolism
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed / genetics
  • Recombinant Fusion Proteins / physiology
  • Sodium Bicarbonate
  • Sterol Regulatory Element Binding Protein 2
  • Sterols / pharmacology*
  • Transcription Factors / drug effects*
  • Transcription Factors / metabolism
  • Transcription, Genetic / genetics
  • Transfection
  • ras Proteins / genetics

Substances

  • DNA, Complementary
  • DNA-Binding Proteins
  • Epitopes
  • Membrane Proteins
  • Recombinant Fusion Proteins
  • SREBF2 protein, human
  • Sterol Regulatory Element Binding Protein 2
  • Sterols
  • Transcription Factors
  • Sodium Bicarbonate
  • Cholesterol
  • Endopeptidases
  • ras Proteins