Lipid composition of myelin and protein--lipid complex in a neurological rabbit mutant.

The neurological mutant of the paralytic tremor "pt" rabbit is characterized by a reduced amount of myelin to 25-30% of control with no change in specific activity for 2',3'-cyclic nucleotide phosphodiesterase. The ratio of total lipids to protein was higher in "pt" rabbit myelin than in control by about 20%. Analysis of the lipid composition of "pt" rabbit myelin indicated a significantly lower level of galactolipids (by about 30%) and a higher level of gangliosides compared to control. The percentage composition of phospholipids in "pt" myelin was characterized by a lower proportion of acidic phospholipids (polyphosphoinositides, phosphatidic acid, phosphatidylserine). The protein-lipid complex in "pt" rabbit myelin was decreased by about 10-15% compared to control. The ratio by weight of protein to lipid in myelin was 0.24 and 0.20 in control and "pt" rabbit, respectively, but in protein-lipid complex isolated from myelin it was 1.73 in control and 0.72 in "pt" rabbit. Protein-lipid complex isolated from myelin of "pt" rabbit brain contained about 34% less protein and about 16% less acidic phospholipids but neutral phospholipids were increased by 24%. The lipid abnormalities in "pt" rabbit myelin and in the composition of protein-lipid complex may be responsible for the disturbances of myelin formation and compaction in "pt" rabbit.