Transmembrane Protein 147 (TMEM147) Is a Novel Component of the Nicalin-NOMO Protein Complex

J Biol Chem. 2010 Aug 20;285(34):26174-81. doi: 10.1074/jbc.M110.132548. Epub 2010 Jun 10.

Abstract

Nicastrin and its relative Nicalin (Nicastrin-like protein) are both members of larger protein complexes, namely gamma-secretase and the Nicalin-NOMO (Nodal modulator) complex. The gamma-secretase complex, which contains Presenilin, APH-1, and PEN-2 in addition to Nicastrin, catalyzes the proteolytic cleavage of the transmembrane domain of various proteins including the beta-amyloid precursor protein and Notch. Nicalin and its binding partner NOMO form a complex that was shown to modulate Nodal signaling in developing zebrafish embryos. Because its experimentally determined native size (200-220 kDa) could not be satisfyingly explained by the molecular masses of Nicalin (60 kDa) and NOMO (130 kDa), we searched in affinity-purified complex preparations for additional components in the low molecular mass range. A approximately 22-kDa protein was isolated and identified by mass spectrometry as transmembrane protein 147 (TMEM147), a novel, highly conserved membrane protein with a putative topology similar to APH-1. Like Nicalin and NOMO, it localizes to the endoplasmic reticulum and is expressed during early zebrafish development. Overexpression and knockdown experiments in cultured cells demonstrate a close relationship between the three proteins and suggest that they are components of the same complex. We present evidence that, similar to gamma-secretase, its assembly is hierarchical starting with the formation of a Nicalin-NOMO intermediate. Nicalin appears to represent the limiting factor regulating the assembly rate by stabilizing the other two components. We conclude that TMEM147 is a novel core component of the Nicalin-NOMO complex, further emphasizing its similarity with gamma-secretase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid Precursor Protein Secretases
  • Animals
  • Endoplasmic Reticulum
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Membrane Glycoproteins
  • Membrane Proteins / metabolism*
  • Multiprotein Complexes
  • Protein Binding
  • Protein Stability
  • Zebrafish
  • Zebrafish Proteins

Substances

  • Intracellular Signaling Peptides and Proteins
  • Membrane Glycoproteins
  • Membrane Proteins
  • Multiprotein Complexes
  • NCLN protein, human
  • NOMO3 protein, human
  • Zebrafish Proteins
  • ncln protein, zebrafish
  • nomo protein, zebrafish
  • transmembrane protein 147, human
  • Amyloid Precursor Protein Secretases