JCB logo
Quantitative Colocalization Analysis Software
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 449K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mullock, B. M.
Right arrow Articles by Luzio, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mullock, B. M.
Right arrow Articles by Luzio, J.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

© The Rockefeller University Press, 0021-9525/1998//591 $5.00
The Journal of Cell Biology, Volume 140, Number 3, , 1998 591-601

Article

Fusion of Lysosomes with Late Endosomes Produces a Hybrid Organelle of Intermediate Density and Is NSF Dependent



Barbara M. Mullock, Nicholas A. Bright, Clare W. Fearon, Sally R. Gray, and J. Luzio

Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2QR, United Kingdom

Using a cell-free content mixing assay containing rat liver endosomes and lysosomes in the presence of pig brain cytosol, we demonstrated that after incubation at 37°C, late endosome–lysosome hybrid organelles were formed, which could be isolated by density gradient centrifugation. ImmunoEM showed that the hybrids contained both an endocytosed marker and a lysosomal enzyme. Formation of the hybrid organelles appeared not to require vesicular transport between late endosomes and lysosomes but occurred as a result of direct fusion. Hybrid organelles with similar properties were isolated directly from rat liver homogenates and thus were not an artifact of cell-free incubations. Direct fusion between late endosomes and lysosomes was an N-ethylmaleimide–sensitive factor– dependent event and was inhibited by GDP-dissociation inhibitor, indicating a requirement for a rab protein. We suggest that in cells, delivery of endocytosed ligands to an organelle where proteolytic digestion occurs is mediated by direct fusion of late endosomes with lysosomes. The consequences of this fusion to the maintenance and function of lysosomes are discussed.

Abbreviations used in this paper: Av-ASF, avidin-asialofetuin; bpIgA, biotinylated polymeric IgA; GDI, GDP dissociation inhibitor; GMP-PNP, 5'-guanylylimidodiphosphate; MPR, cation-independent mannose 6-phosphate receptor; NDGA, nordihydroguaiaretic acid; NEM, N-ethylmaleimide; NSF, NEM-sensitive factor; PI3-K, phosphatidylinositol 3-kinase; SNAP, soluble NSF attachment protein.

This work was funded by the Medical Research Council and Smith Kline Beecham.

Received for publication 2 May 1997 and in revised form 15 December 1997.

B.M. Mullock and N.A. Bright contributed equally to this work.

Address all correspondence to Paul Luzio, Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2QR, UK. Tel.: +44-1223-336780. Fax: +44-1223-330598. E-mail: jpl10{at}cam.ac.uk


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents