Ben Baruch G, Paz A, Marciano D, Egozi Y, Haklai R, Kloog Y
Department of Biochemistry, George S. Wise Faculty of Life Sciences, Meir Hospital, Kfar Saba, Israel.
Biochem Biophys Res Commun. 1993 Aug 31;195(1):282-8. doi: 10.1006/bbrc.1993.2042.
Isoprenylated protein methyltransferase, the enzyme which catalyzes the reversible methylation of signal transducing G-proteins was studied in nine brain regions of the rat brain using S-farnesyl cysteine analogs as substrates. Enzyme activity, as determined with N-acetyl-S-farnesyl-L-cysteine (AFC) was found in the nuclear, synaptosomal and microsomal fractions of all brain regions but not in the cytosol. The enzyme is a unique methyltransferase with respect to its brain distribution. The rank order of activity of the enzyme is cerebellum >> midbrain > medulla > forebrain regions, where activities in cerebellar synaptosomal and nuclear fractions (28-32 pmol AFC [methyl-3H]ester formed/min/mg prot) are 20 to 30 times higher than those of the corresponding fraction of the forebrain regions. This distribution is reminiscent of that of neurotransmitter receptors and signal transduction molecules and suggests a regulatory role for the enzyme, particularly in the cerebellum.
使用S-法尼基半胱氨酸类似物作为底物，在大鼠脑的九个脑区研究了异戊二烯化蛋白甲基转移酶，该酶催化信号转导G蛋白的可逆甲基化。用N-乙酰基-S-法尼基-L-半胱氨酸（AFC）测定的酶活性在所有脑区的核、突触体和微粒体部分中均有发现，但在细胞溶质中未发现。就其脑部分布而言，该酶是一种独特的甲基转移酶。该酶的活性排序为小脑>>中脑>延髓>前脑区域，其中小脑突触体和核部分的活性（每分钟每毫克蛋白形成28 - 32 pmol AFC [甲基-3H]酯）比前脑区域相应部分的活性高20至30倍。这种分布让人联想到神经递质受体和信号转导分子的分布，并表明该酶具有调节作用，尤其是在小脑中。
