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The RGD motif and the C-terminal segment of proprotein convertase 1 are critical for its cellular trafficking but not for its intracellular binding to integrin α5β1
被引:32
作者:
Rovère, C
Luis, J
Lissitzky, JC
Basak, A
Marvaldi, J
Chrétien, M
Seidah, NG
机构:
[1] Univ Montreal, Clin Res Inst Montreal, Biochem Neuroendocrinol Lab, Montreal, PQ H2W 1R7, Canada
[2] Univ Montreal, Clin Res Inst Montreal, Lab Mol Neuroendocrinol, Montreal, PQ H2W 1R7, Canada
[3] Univ Montreal, Clin Res Inst Montreal, Prot Engn Network Ctr Excellence, Montreal, PQ H2W 1R7, Canada
[4] CNRS, Biochim Cellulaire Lab, Unite Propre Rech Enseignement Super Associee 603, Fac Pharm, F-13385 Marseille 05, France
[5] Hop St Marguerite, INSERM, U387, F-13009 Marseille 29, France
关键词:
D O I:
10.1074/jbc.274.18.12461
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
Cellular trafficking of subtilisin/kexin-like precursor convertases (PCs) may be regulated by a number of motifs, some of which are present within the P-domain and in the C-terminal sequence. Six of the seven known PCs contain a conserved RGD sequence within the P domain. In order to investigate the functional importance of this motif, we generated mutants of PC1 that contain a Myc tag epitope inserted between the prosegment and the catalytic subunit. Cellular expression of vaccinia virus recombinants revealed that this tag did not seem to influence the autocatalytic conversion of proPC1 into PC1 or its bioactivity, The two PC1 variants produced possess either the wild type RGD sequence or its RGE mutant. Stable transfectants of these variants in AtT20 cells revealed that similar to the wild type enzyme, PC1-RGD-Myc is sorted to secretory granules. In contrast, PC1-RGE-Mye exits the cell via the constitutive secretory pathway. In vitro, a 14-mer peptide spanning the RGD sequence of PC1, but not its RGE mutant, binds to cell surface vitronectin-binding integrins of Chinese hamster ovary cells. However, within the endoplasmic reticulum and in an RGD-independent fashion, integrin alpha(5)beta(1), associates primarily with the zymogens proPC1, proPC1-Delta C (missing the C-terminal 137 residues), as well as proPC(2). Thus, the observed discrimination between the secretion routes of PC1-RGD and PC1-RGE does not implicate integrins such as alpha(5)beta(1).
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页码:12461 / 12467
页数:7
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