Transmembrane protein 147 (TMEM147) is a novel component of the Nicalin-NOMO protein complex.
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.
Dettmer
Ulf
U
German Center for Neurodegenerative Diseases (DZNE) and the Adolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-University, D-80336 Munich, Germany.
Kuhn
Peer-Hendrik
PH
Abou-Ajram
Claudia
C
Lichtenthaler
Stefan F
SF
Krüger
Marcus
M
Kremmer
Elisabeth
E
Haass
Christian
C
Haffner
Christof
C
D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D004721:Endoplasmic Reticulum; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D046912:Multiprotein Complexes; D011485:Protein Binding; D055550:Protein Stability; D015027:Zebrafish; D029961:Zebrafish Proteins
D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; C520019:NCLN protein, human; C501109:NOMO3 protein, human; D029961:Zebrafish Proteins; C501106:ncln protein, zebrafish; C501108:nomo protein, zebrafish; C552367:transmembrane protein 147, human; D053829:Amyloid Precursor Protein Secretases