The assembly of CD1e is controlled by an N-terminal propeptide which is processed in endosomal compartments.
CD1e displays unique features in comparison with other CD1 proteins. CD1e accumulates in Golgi compartments of immature dendritic cells and is transported directly to lysosomes, where it is cleaved into a soluble form. In these latter compartments, CD1e participates in the processing of glycolipid antigens. In the present study, we show that the N-terminal end of the membrane-associated molecule begins at amino acid 20, whereas the soluble molecule consists of amino acids 32-333. Thus immature CD1e includes an N-terminal propeptide which is cleaved in acidic compartments and so is absent from its mature endosomal form. Mutagenesis experiments demonstrated that the propeptide controls the assembly of the CD1e alpha-chain with beta(2)-microglobulin, whereas propeptide-deleted CD1e molecules are immunologically active. Comparison of CD1e cDNAs from different mammalian species indicates that the CD1e propeptide is conserved during evolution, suggesting that it may also optimize the generation of CD1e molecules in other species.
Maître
Blandine
B
INSERM, U.725 Biology of Human Dendritic Cells, Strasbourg, , France.
Angénieux
Catherine
C
Wurtz
Virginie
V
Layre
Emilie
E
Gilleron
Martine
M
Collmann
Anthony
A
Mariotti
Sabrina
S
Mori
Lucia
L
Fricker
Dominique
D
Cazenave
Jean-Pierre
JP
van Dorsselaer
Alain
A
Gachet
Christian
C
de Libero
Gennaro
G
Puzo
Germain
G
Hanau
Daniel
D
de la Salle
Henri
H
D000595:Amino Acid Sequence; D000596:Amino Acids; D000818:Animals; D018949:Antigens, CD1 / Q000737:chemistry / Q000378:metabolism*; D002451:Cell Compartmentation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004330:Drosophila; D004721:Endoplasmic Reticulum / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals; D012995:Solubility
D000596:Amino Acids; D018949:Antigens, CD1; C417738:CD1e antigen; D050505:Mutant Proteins; D010455:Peptides; D021382:Protein Sorting Signals