HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: M500343-MCP200v1 5/4/686    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Glossary Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sleat, D. E. Articles by Lobel, P. Search for Related Content PubMed PubMed Citation Articles by Sleat, D. E. Articles by Lobel, P. Social Bookmarking                      What's this?

---

Research

Identification of Sites of Mannose 6-Phosphorylation on Lysosomal Proteins^*

David E. Sleat^,,¶, Haiyan Zheng, Meiqian Qian^, and Peter Lobel^,,||

From the Center for Advanced Biotechnology and Medicine and Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854

Most newly synthesized soluble lysosomal proteins contain mannose 6-phosphate (Man-6-P), a specific carbohydrate modification that is recognized by Man-6-P receptors (MPRs) that direct targeting to the lysosome. A number of proteomic studies have focused on lysosomal proteins, exploiting the fact that Man-6-P-containing forms can be purified by affinity chromatography on immobilized MPRs. These studies have identified many known lysosomal proteins as well as many proteins not previously classified as lysosomal. The latter are of considerable biological interest with potential implications for lysosomal function and as candidates for lysosomal storage diseases of unknown etiology. However, a significant problem in interpreting the biological relevance of such proteins has been in distinguishing true Man-6-P glycoproteins from simple contaminants and from proteins associated with true Man-6-P glycoproteins (e.g. protease inhibitors and lectins). In this report, we describe a mass spectrometric approach to the verification of Man-6-phosphorylation based upon LC-MS of MPR-purified proteolytic glycopeptides. This provided a useful tool in validating novel MPR-purified proteins as true Man-6-P glycoproteins and also allowed identification of low abundance components not observed in the analysis of the total Man-6-P glycoprotein mixture. In addition, this approach allowed the global mapping of 99 Man-6-phosphorylation sites from 44 known lysosomal proteins purified from mouse and human brain. This information is likely to provide useful insights into protein determinants for this modification and may be of significant value in protein engineering approaches designed to optimize protein delivery to the lysosome in therapeutic applications such as gene and enzyme replacement therapies.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Qian, D. E. Sleat, H. Zheng, D. Moore, and P. Lobel Proteomics Analysis of Serum from Mutant Mice Reveals Lysosomal Proteins Selectively Transported by Each of the Two Mannose 6-Phosphate Receptors Mol. Cell. Proteomics, January 1, 2008; 7(1): 58 - 70. [Abstract] [Full Text] [PDF]

				H.-L. Liou, S. S. Dixit, S. Xu, G. S. Tint, A. M. Stock, and P. Lobel NPC2, the Protein Deficient in Niemann-Pick C2 Disease, Consists of Multiple Glycoforms That Bind a Variety of Sterols J. Biol. Chem., December 1, 2006; 281(48): 36710 - 36723. [Abstract] [Full Text] [PDF]

				M. C. D. Valle, D. E. Sleat, I. Sohar, T. Wen, J. E. Pintar, M. Jadot, and P. Lobel Demonstration of Lysosomal Localization for the Mammalian Ependymin-related Protein Using Classical Approaches Combined with a Novel Density Shift Method J. Biol. Chem., November 17, 2006; 281(46): 35436 - 35445. [Abstract] [Full Text] [PDF]

				D. E. Sleat, Y. Wang, I. Sohar, H. Lackland, Y. Li, H. Li, H. Zheng, and P. Lobel Identification and Validation of Mannose 6-Phosphate Glycoproteins in Human Plasma Reveal a Wide Range of Lysosomal and Non-lysosomal Proteins Mol. Cell. Proteomics, October 1, 2006; 5(10): 1942 - 1956. [Abstract] [Full Text] [PDF]

				J.-Y. Lu and S. L. Hofmann Thematic review series: Lipid Posttranslational Modifications. Lysosomal metabolism of lipid-modified proteins J. Lipid Res., July 1, 2006; 47(7): 1352 - 1357. [Abstract] [Full Text] [PDF]