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Salvage of catabolic products in ganglioside metabolism: a study on rat cerebellar granule cells in culture
Author(s) -
Riboni Laura,
Bassi Rosaria,
Prinetti Alessandro,
Tettamanti Guido
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00772-7
Subject(s) - granule (geology) , catabolism , ganglioside , metabolism , biochemistry , chemistry , tritium , stereochemistry , biology , paleontology , physics , nuclear physics
Cerebellar granule cells in culture were subjected to a pulse (0.5–4 h)‐chase (0–4 h) of 10 −6 M [ 3 H]ganglioside GM1 carrying the radioactive label at the level of NeuAc ([ 3 H‐NeuAc]GM1), Sph ([ 3 H‐Sph]GM1) or Gal ([ 3 H‐GallGMl) and the formed [ 3 H]metabolites were determined. With all forms of [ 3 H]GM1, there was formation of [ 3 H]catabolites, including [ 3 H]H 2 O and [ 3 H]biosynthetic products obtained by recycling of [ 3 H]NeuAc, [ 3 H]Sph and [ 3 H]Gal released during intralysosomal ganglioside degradation (salvage processes). Much higher amounts of [ 3 MH 2 O were produced from [ 3 H‐Gal]GM1 than [ 3 H‐Sph]GM1 and [ 3 H‐NeuAc]GM1; conversely, more products from salvage processes (polysialogangliosides GD1a, GDlb, GTlb, O‐acetylated GT1b, protein‐bound radioactivity) were obtained with [ 3 H‐NeuAc]GM1; than the two other forms of [ 3 H]GM1, Liberated [ 3 H]NeuAc produced 10‐fold less tritiated water and 10‐fold higher salvage products than [ 3 H]Gal. Using [ 3 H‐NeuAc]GM1; granule cells appeared to metabolize 7.7% of membrane‐incorporated exogenous GM1 per hour with a high degree of NeuAc recycling and the calculated metabolic half‐life was 6.5 h.