Skip Navigation



Glycobiology Advance Access published online on August 6, 2007
Glycobiology, doi:10.1093/glycob/cwm083
This Article
Right arrow Advance Access manuscript (PDF) Freely available
Right arrow Supplementary Data
Right arrow All Versions of this Article:
17/10/1084    most recent
cwm083v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Kuokkanen, E.
Right arrow Articles by Heikinheimo, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kuokkanen, E.
Right arrow Articles by Heikinheimo, P.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2007. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

Characterisation and subcellular localisation of human neutral class II {alpha}-mannosidase

Elina Kuokkanen, Wesley Smith, Marika Mäkinen, Heidi Tuominen, Maija Puhka, Eija Jokitalo, Sandrine Duvet, Thomas Berg1 and Pirkko Heikinheimo§

Department of Biochemistry and Food Chemistry, University of Turku, FIN-20014, Finland
Institute of Biotechnology, University of Helsinki, FIN-00014, Finland
Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, GDR CNRS 2590, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
Department of Medical Biochemistry, University of Troms{oslash}, N-9037 Troms{oslash}, Norway

§ Corresponding author: Tel: +358 9 191 58957, Fax: +358 9 191 59940, email: pirkko.heikinheimo{at}helsinki.fi

Received on April 10, 2007; accepted on July 31, 2007

A glycosyl hydrolase family 38 enzyme, neutral {alpha}-mannosidase, has been proposed to be involved in hydrolysis of cytosolic free oligosaccharides originating either from ER-misfolded glycoproteins or the N-glycosylation process. Although this enzyme has been isolated from the cytosol, it has also been linked to the ER by subcellular fractionations. We have studied the subcellular localisation of neutral {alpha}-mannosidase by immunofluorescence microscopy and characterised the human recombinant enzyme with natural substrates to elucidate the biological function of this enzyme. Immunofluorescence microscopy showed neutral {alpha}-mannosidase to be absent from the ER, lysosomes and autophagosomes, and being granularly distributed in the cytosol. In experiments with fluorescent recovery after photo bleaching neutral {alpha}-mannosidase had slower than expected two-phased diffusion in the cytosol. This result together with the granular appearance in immunostaining suggests that portion of the neutral {alpha}-mannosidase pool is somehow complexed. The purified recombinant enzyme is a tetramer and has a neutral pH optimum for activity. It hydrolysed Man9GlcNAc to Man5GlcNAc in presence of Fe2+, Co2+ and Mn2+, and uniquely to neutral {alpha}-mannosidases from other organisms, the human enzyme was more activated by Fe2+ than Co2+. Without activating cations the main reaction product was Man8GlcNAc, and Cu2+ completely inhibited neutral {alpha}-mannosidase. Our findings from enzyme-substrate characterizations and subcellular localisation studies support the suggested role for neutral {alpha}-mannosidase in hydrolysis of soluble cytosolic oligomannosides.

Key words: cytosolic enzymes / free oligosaccharides / glycoside hydrolase family 38 / M2C1 / N-glycosylation


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 GlycobiologyHome page
M. M Desko, D. A Gross, and J. J Kohler
Effects of N-glycosylation on the activity and localization of GlcNAc-6-sulfotransferase 1
Glycobiology, October 1, 2009; 19(10): 1068 - 1077.
[Abstract] [Full Text] [PDF]

Home page
 GlycobiologyHome page
I. Chantret and S. E H Moore
Free oligosaccharide regulation during mammalian protein N-glycosylation
Glycobiology, March 1, 2008; 18(3): 210 - 224.
[Abstract] [Full Text] [PDF]

Home page
 JCBHome page
M. Puhka, H. Vihinen, M. Joensuu, and E. Jokitalo
Endoplasmic reticulum remains continuous and undergoes sheet-to-tubule transformation during cell division in mammalian cells
J. Cell Biol., December 3, 2007; 179(5): 895 - 909.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.