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Subcellular Localization and Partial Purification of Prelamin a Endoprotease: An Enzyme Which Catalyzes the Conversion of Farnesylated Prelamin a to Mature Lamin A

The nuclear lamina protein, lamin A is produced by proteolytic cleavage of a 74 kDa precursor protein, prelamin A. The conversion of this precursor to mature lamin A is mediated by a specific endoprotease, prelamin A endoprotease. Subnuclear fractionation indicates that the prelamin A endoprotease is localized at the nuclear membrane. The enzyme appears to be an integral membrane protein, as it can only be removed from the nuclear envelope with detergent. It is effectively solubilized by the detergent n-octyl-beta-D-glucopyranoside and can be partially-purified (approximately 1200-fold) by size exclusion and cation exchange (Mono S) chromatography. Prelamin A endoprotease from HeLa cells was eluted from Mono S with 0.3 M sodium chloride as a single peak of activity. SDS-PAGE analysis of this prelamin A endoprotease preparation shows that it contains one major polypeptide at 65 kDa and smaller amounts of a second 68 kDa polypeptide. Inhibition of the enzyme activity in this preparation by specific serine protease inhibitors is consistent with the enzyme being a serine protease.

Identiferoai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-2-1009
Date30 April 1999
CreatorsKilic, Fusun, Johnson, D A., Sinensky, M.
PublisherDigital Commons @ East Tennessee State University
Source SetsEast Tennessee State University
Detected LanguageEnglish
Typetext
SourceETSU Faculty Works

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