Evidence for a Link Between Peroxisomes and the Nonspecific Lipid Transfer Protein (Sterol Carrier Protein 2) in Rat and Human Liver
Antibodies against the nonspecific lipid transfer protein (nsL-TP) are cross-reactive with a high-molecular weight protein(s) found in the 105,000 x g supernatant and peroxisomes from rat and human liver. Levels of nsL-TP in Morris hepatoma 7777 and in the liver of Zellweger patients are greatly reduced as compared to controls (i.e. ten- to twenty-fold reduction). These tissues which are deficient in peroxisomes, do contain the high-molecular weight protein (s). This suggests that the occurrence of nsL-TP may depend on the presence of peroxisomes.
Levels of nsL-TP in the Leydig cells of rat testis are under hormonal control. Stimulation of rat tumor Leydig cells with luteinizing hormone doubled the levels of nsL-TP within two minutes under conditions where protein synthesis was inhibited. It remains to be established whether this post-translational processing involves cleavage of a high-molecular weight protein.
KeywordsCholesterol Fractionation Cycloheximide Spiro Pregnenolone
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