Limited and selective transfer of plasma membrane glycoproteins to membrane of secondary lysosomes.

Abstract

Abstract. Radioactive galactose, covalenfly bound to cell surface glycoconjugates on mouse macrophage cells, P388D~, was used as a membrane marker to study the composition, and the kinetics of exchange, of plasma membrane-derived constituents in the membrane of secondary lysosomes. Secondary lysosomes were separated from endosomes and plasma membrane on self-forming Percoll density gradients. Horseradish peroxidase, taken up by fluid-phase pinocytosis, served as a vesicle contents marker to monitor transfer of endosomal contents into secondary lysosomes. Concurrently, the fraction of plasma membrane-derived label in secondary lysosomes increased by first order kinetics (k = [56 min]-q from <0.1% (background level) to a steady-state level of ,x,2.5% of the total label. As analyzed by NaDodSO4 PAGE, labeled molecules of Mr 160-190 kD were depleted and of Mr 100-120 kD were enriched in lysosome membrane compared with the relative composition of label on the cell surface. No corresponding selectivity was observed for the degradation of label, with all Mr classes being affected to the same relative extent. The results indicate that endocytosis-derived transfer of plasma membrane constituents to secondary lysosomes is a limited and selective process, and that only ~1% of internalized membrane is recycled via a membrane pool of secondary lysosomes.

Kinetics of endocytosis and recycling of the GPI-anchored variant surface glycoprotein inTrypanosoma brucei

“…As judged by either fluorescence or by electron microscopic evidence, neither the lysosome nor the Golgi complex are stations in the recycling pathway of VSG. Similarly, cell surface-derived glycoproteins on endosomes of macrophages are efficiently recycled at two pre-lysosomal stages (Thilo et al, 1995) without reaching the lysosomal membrane (Haylett and Thilo, 1986).…”

The many niches and strategies used by pathogenic mycobacteria for survival within host macrophages

“…Likewise, the mechanism whereby M. avium re-establishes the close apposition with the phagosome membrane all around is unknown at present. It may be provided by specific interactions between the mycobacterial surface and macrophage surface-derived glycoproteins, of which it has been shown that a small and selective fraction is recycled through the membrane of lysosomes (Haylett and Thilo, 1986).…”

Dynamin-dependent Transferrin Receptor Recycling by Endosome-derived Clathrin-coated Vesicles

“…TfR might be either actively or passively incorporated into clathrin-coated vesicles. Even tailless TfR should recycle almost quantitatively because, of all endocytosed membrane, ϳ95% is eventually recycled to the plasma membrane and only ϳ5% is targeted to lysosomes (Haylett and Thilo, 1986;Draye et al, 1988). Active recruitment into the recycling pathway thus seems not to be required for a single round of endocytosis.…”