GM3 ganglioside in various tissues of rabbit. Tissue-specific distribution of N-glycolylneuraminic acid-containing GM31.

Molecular species and concentrations of GM3 ganglioside in rabbit tissues, brain, thymus, lung, liver, stomach, intestine, kidney, testis, muscle, and erythrocytes were determined. The highest concentration was found in lung (431.7 nmol/g wet tissue). With the exceptions of brain, thymus, and erythrocytes, GM3 was the dominant ganglioside and comprised more than 50% of the total gangliosides. In brain and thymus, GM3 composed 0.76% and 17.28% of the total gangliosides, respectively. The sialic acid composition of GM3 was determined by mild methanolysis and neuraminidase treatment combined with either permethylation or trimethylsilylation. N-Glycolylneuraminic acid-containing GM3 was found in thymus, lung, kidney, and intestine in addition to N-acetylneuraminic acid-containing GM3, but N-acetylneuraminic acid was the sole sialic acid of GM3 in the other tissues. Sixty-four percent of the thymus GM3 consisted of N-glycolylneuraminic acid. High concentrations of C-20 sphingosine and stearic acid were characteristic for brain GM3 and the major long chain base of the other tissues was C-18 spingosine. The fatty acid composition of GM3 varied in each tissue. The difference in mobility on a thin-layer plate was due to the difference in its molecular constitution, being derived from a combination of fatty acid, long chain base, and sialic acid.