Domains b' and a' of protein disulfide isomerase fulfill the minimum requirement for function as a subunit of prolyl 4-hydroxylase. The N-terminal domains a and b enhances this function and can be substituted in part by those of ERp57.

Pirneskoski, Annamari and Ruddock, Lloyd W. and Klappa, Peter and Freedman, Robert B. and Kivirikkos, Kari I. and Koivunen, Peppi (2001) Domains b' and a' of protein disulfide isomerase fulfill the minimum requirement for function as a subunit of prolyl 4-hydroxylase. The N-terminal domains a and b enhances this function and can be substituted in part by those of ERp57. Journal of Biological Chemistry, 276 (14). pp. 11287-11293. ISSN 0021-9258. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1074/jbc.M010656200

Abstract

Protein disulfide isomerase (PDI) is a modular polypeptide consisting of four domains, a, b, b', and a', plus an acidic C-terminal extension, c. PDI carries out multiple functions, acting as the beta subunit in the animal prolyl 4-hydroxylases and in the microsomal triglyceride transfer protein and independently acting as a protein folding catalyst. We report here that the minimum sequence requirement for the assembly of an active prolyl 4-hydroxylase alpha(2)beta(2) tetramer in insect cell coexpression experiments is fulfilled by the PDI domain construct b'a' but that the sequential addition of the b and a domains greatly increases the level of enzyme activity obtained. In the assembly of active prolyl 4-hydroxylase tetramers, the a and b domains of PDI, but not b' and a', can in part be substituted by the corresponding domains of ERp57, a PDI isoform that functions naturally in association with the lectins calnexin and calreticulin. The a' domain of PDI could not be substituted by the PDI a domain, suggesting that both b' and a' domains contain regions critical for prolyl 4-hydroxylase assembly. All PDI domain constructs and PDI/ERp57 hybrids that contain the b' domain can bind the 14-amino acid peptide Delta-somatostatin, as measured by cross-linking; however, binding of the misfolded protein "scrambled" RNase required the addition of domains ab or a' of PDI. The human prolyl 4-hydroxylase alpha subunit has at least two isoforms, alpha(I) and alpha(II), which form with the PDI polypeptide the (alpha(I))(2)beta(2) and (alpha(II))(2)beta(2) tetramers. We report here that all the PDI domain constructs and PDI/ERp57 hybrid polypeptides tested were more effectively associated with the alpha(II) subunit than the alpha(I) subunit.

Item Type: Article
Subjects: Q Science > Q Science (General)
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Faculties > Science Technology and Medical Studies > School of Biosciences > Protein Science Group
Depositing User: Peter Klappa
Date Deposited: 29 Aug 2008 11:03
Last Modified: 24 Jun 2014 11:00
Resource URI: http://kar.kent.ac.uk/id/eprint/3867 (The current URI for this page, for reference purposes)
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