ABCB2 p.Lys463Ala
| Predicted by SNAP2: | A: D (71%), C: D (63%), D: D (80%), E: D (71%), F: D (75%), G: D (75%), H: D (63%), I: D (71%), L: D (75%), M: D (66%), N: D (71%), P: D (85%), Q: N (57%), R: N (78%), S: D (66%), T: D (66%), V: D (63%), W: D (75%), Y: D (75%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, L: D, M: D, N: D, P: D, Q: D, R: N, S: D, T: D, V: D, W: D, Y: D, |
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[hide] Multiple residues in the transmembrane helix and c... J Biol Chem. 2007 Mar 30;282(13):9401-10. Epub 2007 Jan 23. Papadopoulos M, Momburg F
Multiple residues in the transmembrane helix and connecting peptide of mouse tapasin stabilize the transporter associated with the antigen-processing TAP2 subunit.
J Biol Chem. 2007 Mar 30;282(13):9401-10. Epub 2007 Jan 23., [PMID:17244610]
Abstract [show]
The type I endoplasmic reticulum (ER) glycoprotein tapasin (Tpn) is essential for loading of major histocompatibility complex class I (MHC-I) molecules with an optimal spectrum of antigenic peptides and for stable expression of the heterodimeric, polytopic TAP peptide transporter. In a detailed mutational analysis, the transmembrane domain (TMD) and ER-luminal connecting peptide (CP) of mouse Tpn were analyzed for their capacity to stabilize the TAP2 subunit. Replacement of the TMD of Tpn by TMDs from calnexin or the Tpn-related protein, respectively, completely abolished TAP2 stabilization after transfection of Tpn-deficient cells, whereas TMDs derived from distantly related Tpn molecules (chicken and fish) were functional. A detailed mutational analysis of the TMD and adjacent residues in the ER-luminal CP of mouse Tpn was performed to elucidate amino acids that control the stabilization of TAP2. Single amino acid substitutions, including a conserved Lys residue in the center of the putative TMD, did not affect TAP2 expression levels. Mutation of this Lys plus four additional residues, predicted to be neighbors in an assumed alpha-helical TMD arrangement, abrogated the TAP2-stabilizing capacity of Tpn. In the presence of a wild-type TMD, also the substitution of a highly conserved Glu residue in the CP of Tpn strongly affected TAP2 stabilization. Defective TAP2 stabilization resulted in impaired cell surface expression of MHC-I molecules. This study thus defines a novel, spatially arranged motif in the TMD of Tpn essential for stable expression of the TAP2 protein and a novel protein interaction mode involving an ER-luminal Glu residue close to the membrane.
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No. Sentence Comment
39 To generate the ER retrieval signal mutant K463A/K464A of mTpn, the reverse primer 5Ј-GGCCAAGCTTATTGGGAAGCGG- CTGAGTTCCTGGGAATGGTCAGGCTGGC-3Ј was used together with the same forward primer as above and inserted into mTpn cDNA using XbaI and HindIII.
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ABCB2 p.Lys463Ala 17244610:39:43
status: NEW87 Also, the mTpn[K463A/K464A] mutant was able to substitute WT mTpn, suggesting that ER retrieval/retention is not essential for the TAP2-stabilizing function of Tpn.
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ABCB2 p.Lys463Ala 17244610:87:15
status: NEW238 Since the mutant mTpn[K462A/K463A] was fully functional in terms of TAP2 stabilization, it is conceivable that Tpn acts on TAP in the ER proper and also within the recycling pathway.
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ABCB2 p.Lys463Ala 17244610:238:28
status: NEW237 Since the mutant mTpn[K462A/K463A] was fully functional in terms of TAP2 stabilization, it is conceivable that Tpn acts on TAP in the ER proper and also within the recycling pathway.
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ABCB2 p.Lys463Ala 17244610:237:28
status: NEW