Refinement of the Expression Pattern of a Mouse Homologue of the Porcine 135-kDa α-d-Mannosidase (MAN2B2)

Tascou, Sèmi; Nayernia, Karim; Engel, Wolfgang; Burfeind, Peter

doi:10.1006/bbrc.2000.2868

Cited by 7 publications

(9 citation statements)

References 2 publications

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“…Mouse transcripts encoding the enzyme were found exclusively in type A spermatogonia at stages IX-XI of spermatogenesis (31). In contrast, subsequent studies have shown that transcripts encoding the murine ortholog of the ␣1,6-mannosidase are not restricted to reproductive tissues, but they are ubiquitously expressed (32), consistent with our present data demonstrating a ubiquitous expression of transcripts encoding the human enzyme (Fig. 9).…”

Section: ϩsupporting

confidence: 91%

“…The blots were subsequently hybridized with a radiolabeled human ␤-actin probe (Clontech) to act as an RNA load control for the blots. 32 P-Labeled DNA probes were generated using [ Inhibitor data were collected in triplicate. Lineweaver-Burk plots and Dixon plots were used to transform the kinetic data into values of K m and K i as described previously (12, 39 -41).…”

Section: Methodsmentioning

confidence: 99%

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Characterization of a Human Core-specific Lysosomal α1,6-Mannosidase Involved in N-Glycan Catabolism

Park

Stanton

et al. 2005

Journal of Biological Chemistry

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In humans and rodents, the lysosomal catabolism of core Man 3 GlcNAc 2 N-glycan structures is catalyzed by the concerted action of several exoglycosidases, including a broad specificity lysosomal ␣-mannosidase (LysMan), core-specific ␣1,6-mannosidase, ␤-mannosidase, and cleavage at the reducing terminus by a di-Nacetylchitobiase. We describe here the first cloning, expression, purification, and characterization of a novel human glycosylhydrolase family 38 ␣-mannosidase with catalytic characteristics similar to those established previously for the core-specific ␣1,6-mannosidase (acidic pH optimum, inhibition by swainsonine and 1,4-dideoxy-1,4-imino-D-mannitol, and stimulation by Co 2؉ and Zn 2؉). Substrate specificity studies comparing the novel human ␣-mannosidase with human LysMan revealed that the former enzyme efficiently cleaved only the ␣1-6mannose residue from Man 3 GlcNAc but not Man 3 GlcNAc 2 or other larger high mannose oligosaccharides, indicating a requirement for chitobiase action before ␣1,6-mannosidase activity. In contrast, LysMan cleaved all of the ␣-linked mannose residues from high mannose oligosaccharides except the core ␣1-6mannose residue. ␣1,6-Mannosidase transcripts were ubiquitously expressed in human tissues, and expressed sequence tag searches identified homologous sequences in murine, porcine, and canine databases. No expressed sequence tags were identified for bovine ␣1,6-mannosidase, despite the identification of two sequence homologs in the bovine genome. The lack of conservation in 5-flanking sequences for the bovine ␣1,6-mannosidase genes may lead to defective transcription similar to transcription defects in the bovine chitobiase gene. These results suggest that the chitobiase and ␣1,6-mannosidase function in tandem for mammalian lysosomal N-glycan catabolism.

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Section: ϩsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Characterization of a Human Core-specific Lysosomal α1,6-Mannosidase Involved in N-Glycan Catabolism

Park

Stanton

et al. 2005

Journal of Biological Chemistry

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“…The 135 kDa MAN2B2 precursor is processed into subunits with apparent molecular weights of 63 kDa and 51 kDa, respectively [80]. The mouse ortholog Man2B2 is ubiquitously expressed [81]. Identified in most studies of purified Man6-P glycoproteins, human MAN2B2 has recently been shown to preferentially cleave the core alpha 1,6-mannose residue from the Man3-GlcNAc but not from Man3-GlcNAc2 or larger high mannose oligosaccharides [82].…”

Section: Novel Lysosomal M6p-containing Proteinsmentioning

confidence: 99%

Proteomics of the lysosome

Lübke

Lobel²,

Sleat³

2009

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

238

202

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Defects in lysosomal function have been associated with numerous monogenic human diseases typically classified as lysosomal storage diseases. However, there is increasing evidence that lysosomal proteins are also involved in more widespread human diseases including cancer and Alzheimer disease. Thus, there is a continuing interest in understanding the cellular functions of the lysosome and an emerging approach to this is the identification of its constituent proteins by proteomic analyses. To date, the mammalian lysosome has been shown to contain ~ 60 soluble luminal proteins and ~25 transmembrane proteins. However, recent proteomic studies based upon affinity purification of soluble components or subcellular fractionation to obtain both soluble and membrane components suggest that there may be many more of both classes of protein resident within this organelle than previously appreciated. Discovery of such proteins has important implications for understanding the function and the dynamics of the lysosome but can also lead the way towards the discovery of the genetic basis for human diseases of hitherto unknown etiology. Here, we describe current approaches to lysosomal proteomics and data interpretation and review the new lysosomal proteins that have recently emerged from such studies.

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“…This mannosidase, distinct from the lysosomal a-mannosidase, was initially characterized as isoforms either secreted in the epididymal fluid or associated with sperm membranes [56][57][58]. However, a more recent study demonstrated the ubiquitous expression of the mouse MAN2B2 gene [59]. However, a more recent study demonstrated the ubiquitous expression of the mouse MAN2B2 gene [59].…”

Section: Epididymis Specific á-Mannosidase (M2b2)mentioning

confidence: 99%

Proteomic analysis of human lysosomes: Application to monocytic and breast cancer cells

et al. 2002

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To date, about fifty lysosomal hydrolases have been identified, and most of them are targeted towards the lysosomes through a specific mannose-6-phosphate (M-6-P) tag. As more lysosomal hydrolases were expected to be discovered, we performed a proteomic study of soluble lysosomal proteins. Human cells were induced to secrete M-6-P proteins which were affinity purified on immobilized M-6-P receptor. The purified proteins were resolved by two-dimensional electrophoresis and analyzed by mass spectrometry. Twenty-two proteins were identified, among which 16 were well-known lysosomal hydrolases. The remaining species distributed as follows: epididymis-specific alpha-mannosidase is a new mannosidase homolog, cystatin F and CREG (cellular repressor of E1A-stimulated genes) were previously identified as M-6-P proteins (Journet et al., Electrophoresis 2000, 21, 3411-3419), and the last three, which are not hydrolases, were up to now considered as nonlysosomal. This two-dimensional reference map of human U937 M-6-P proteins was afterwards used for comparison with M-6-P proteins purified either from U937 differentiated into macrophage-like cells, or from human breast cancer MCF7 cells. Phorbol ester induced differentiation of U937 cells led to limited proteolytic cleavage or maturation of a discrete number of hydrolases. Five additional lysosomal hydrolases were identified from MCF7 samples. These results prove the usefulness of such a procedure to analyze the lysosomal content of various cell lines, to discover new M-6-P proteins, as well as to point towards unknown biological processes.

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Refinement of the Expression Pattern of a Mouse Homologue of the Porcine 135-kDa α-d-Mannosidase (MAN2B2)

Cited by 7 publications

References 2 publications

Characterization of a Human Core-specific Lysosomal α1,6-Mannosidase Involved in N-Glycan Catabolism

Characterization of a Human Core-specific Lysosomal α1,6-Mannosidase Involved in N-Glycan Catabolism

Proteomics of the lysosome

Proteomic analysis of human lysosomes: Application to monocytic and breast cancer cells

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