Macklin W B, Campagnoni C W, Deininger P L, Gardinier M V
Mental Retardation Research Center, UCLA Medical Center 90024.
J Neurosci Res. 1987;18(3):383-94. doi: 10.1002/jnr.490180302.
The gene for the mouse myelin proteolipid protein has been isolated and the seven exons have been sequenced. Since the sequence of a rat proteolipid protein cDNA and partial sequence of the human proteolipid protein gene have been determined, it was possible to demonstrate a very high degree of conservation for the proteolipid protein gene exons among species. While there are some nucleotide changes, the protein coding region of the mouse gene encodes protein that is totally conserved relative to both rat and human proteolipid proteins. The regulatory and noncoding regions of the proteolipid protein gene are also highly conserved. The upstream regulatory and 5'-noncoding region of the gene is 92% homologous to the comparable region of the human proteolipid protein gene, and the 3'-noncoding region of the mouse gene is approximately 90% homologous to a rat proteolipid protein cDNA through 2,200 nucleotides of 3'-noncoding DNA. S1 nuclease protection experiments indicated that the major 5'-end for proteolipid protein mRNAs from mouse, rat, human, or baboon is approximately 147-160 nucleotides upstream from the initial methionine codon of the protein coding region. Other S1 nuclease protection experiments indicated the possible existence of an alternative splice site within exon 3, which may produce mRNA for DM20. This mRNA is approximately 100 nucleotides shorter than that for the proteolipid protein, and it is missing the latter half of exon 3, that is, amino acids 116-150 of the proteolipid protein sequence.
小鼠髓鞘蛋白脂蛋白的基因已被分离出来，并且对其7个外显子进行了测序。由于已经确定了大鼠蛋白脂蛋白cDNA的序列以及人类蛋白脂蛋白基因的部分序列，因此有可能证明物种间蛋白脂蛋白基因外显子具有高度的保守性。虽然存在一些核苷酸变化，但小鼠基因的蛋白质编码区所编码的蛋白质相对于大鼠和人类的蛋白脂蛋白是完全保守的。蛋白脂蛋白基因的调控区和非编码区也高度保守。该基因的上游调控区和5'-非编码区与人类蛋白脂蛋白基因的相应区域有92%的同源性，小鼠基因的3'-非编码区与大鼠蛋白脂蛋白cDNA通过2200个核苷酸的3'-非编码DNA有大约90%的同源性。S1核酸酶保护实验表明，来自小鼠、大鼠、人类或狒狒的蛋白脂蛋白mRNA的主要5'端位于蛋白质编码区起始甲硫氨酸密码子上游约147 - 160个核苷酸处。其他S1核酸酶保护实验表明外显子3内可能存在一个可变剪接位点，这可能产生DM20的mRNA。这种mRNA比蛋白脂蛋白的mRNA短约100个核苷酸，并且缺失了外显子3的后半部分，即蛋白脂蛋白序列中的氨基酸116 - 150。
