Mechanistic study of modulation of SR Ca2+-ATPpase activity by gangliosides GM1 and GM3 through some biophysical measurements.
On the basis of confirming the antagonistic effects of GM1 and GM3 on the activity of Ca2+-ATPase, we further demonstrated that some of the components of these two gangliosides, including sialic acid (NeuNAc), asialo-GM1, asialo-GM3 and ceramide, failed to show any effects on the activity of Ca2+-ATPase. Thus it is apparent that the intact molecules of these two gangliosides with their specific conformations were needed to perform their effects on Ca2+-ATPase. From the fluorescence resonance energy transfer measurements, the energy transfer between Cys 670/674 and Lys 515 was decreased by GM1 and increased by GM3, indicating GM1 induced the conformation of the hydrophilic region of Ca2+-ATPase to be less compact, while GM3 induced it to be more compact. From the CD spectra measurements, GM1 and GM3 both reduced the content of alpha-helical structures of Ca2+-ATPase, but GM1 caused a stronger decrease than that of GM3. Using DPH as the probe, we found that the membrane lipid fluidity of the proteoliposomes containing Ca2+-ATPase was decreased by GM1 and tend to increase by GM3.
Wang
Y
Y
Dept. of Biochemistry, Dalian Medical University, China.
Tsui
Z
Z
Yang
F
F
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D004735:Energy Transfer; D005456:Fluorescent Dyes; D005677:G(M1) Ganglioside / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D005679:G(M3) Ganglioside / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D011487:Protein Conformation / Q000187:drug effects; D011510:Proteolipids; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D013050:Spectrometry, Fluorescence
D005456:Fluorescent Dyes; D005679:G(M3) Ganglioside; D011510:Proteolipids; C020485:proteoliposomes; D005677:G(M1) Ganglioside; D000252:Calcium-Transporting ATPases