title: Relationship between the regulation of membrane enzyme activities by gangliosides and a possible ganglioside segregation in membrane microdomains.
abstract: Laser and neutron scattering experiments showed that in mixed micelles of ganglioside GM2 and GT1b, a membrane mimicking system, the segregation of gangliosides may occur spontaneously. Photolabeling experiments using nitrophenylazide containing ganglioside GM1 proved that gangliosides added to cells in culture enter the cell and bind to its membrane as components of microdomains, which specifically interact with a protein of about 30 kDa. This suggests that ganglioside segregation may be a natural phenomenon. Gangliosides when added to granule cells in culture led to increase in protein phosphorylation, the effect exerted being related to the amount of ganglioside molecules inserted stably into the cell lipid layer and an increase of 0.7% of the cell original ganglioside content promoted an increase of 57% in the incorporation of 32P into cell membrane proteins. From the above results a possible relationship between ganglioside segregation and involvement of ganglioside in enzyme activity control is suggested.
authors.affiliation: Department of Medical Chemistry and Biochemistry Medical School, University of Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Sonnino
authors.forename: V
authors.initials: V
authors.lastname: Chigorno
authors.forename: M
authors.initials: M
authors.lastname: Valsecchi
authors.forename: R
authors.initials: R
authors.lastname: Bassi
authors.forename: D
authors.initials: D
authors.lastname: Acquotti
authors.forename: L
authors.initials: L
authors.lastname: Cantu
authors.forename: M
authors.initials: M
authors.lastname: Corti
authors.forename: G
authors.initials: G
authors.lastname: Tettamanti
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism*; D002478:Cells, Cultured; D005732:Gangliosides / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008567:Membranes, Artificial; D008823:Micelles; D008969:Molecular Sequence Data; D010766:Phosphorylation
chemical_list: D005732:Gangliosides; D008565:Membrane Proteins; D008567:Membranes, Artificial; D008823:Micelles