STRUCTURE-FUNCTION RELATIONSHIPS OF LYSOSOMAL ENZYMES

I.摩洛哥犹太人口中泰-萨克斯的发病率较高 疾病。我们已经检查了6名无关的摩洛哥携带者， 我发现了三种HEXA基因突变：(1)Leu(181)-Gt；Stop突变 在一个载体中，(2)两个载体中的Arg(170)-Glu改变和(3) 位于第304位(Delta-F)的苯丙氨酸密码子的框内缺失 其中三艘航母。 II.小鼠HEXB基因的完整组织和大多数 已经建立了HEXA基因。这使得建造 利用基因打靶载体“敲除”HEX基因的研究 小鼠胚胎干细胞，并最终产生小鼠模型 G(M2)神经节苷脂增多症。 III.正常和异常蛋白质保留在细胞内的机制 测定了内质网(ER)。这种蛋白质发出的信号是 指定羧酸酯酶家族的成员是分泌的还是 保留在ER中的基因已被确定。这些保留信号是 酵母信号的变体(HDEL)以前被认为在 哺乳动物细胞。 我们还发现，β-糖基化的α-亚基- 己糖氨酸酶经历了一条改变的折叠途径，导致 形成不可溶的、不适当的二硫键结合的聚集体， 被保留在急诊室。不适当折叠的蛋白质会结合到 BiP/GRP 70在内质网中起着分子支架作用。

I. The Moroccan Jewish population has an elevated incidence of Tay-Sachs disease. We have examined 6 unrelated Moroccan carriers of the disease and have identified three HEXA gene mutations: (1) a Leu(181)->Stop mutation in one carrier, (2) an Arg(170)->Glu change in two of the carriers and (3) an in-frame deletion of a phenylalanine codon at position 304 (delta-F) in three of the carriers. II. The complete organization of the murine HEXB gene and the majority of the HEXA gene has been established. This has allowed the construction of gene targeting vectors for the purpose of "knocking out" the HEX genes in mouse embryonic stem cells and for ultimately producing mouse models of the G(M2) gangliosidoses. III. Mechanisms by which normal and abnormal proteins are retained in the endoplasmic reticulum (ER) have been determined. The protein signals that specify whether members of a family of carboxylesterases are secreted or retained in the ER have been identified. These retention signals are variants of the yeast signal (HDEL) previously thought not to function in mammalian cells. We have also found that the unglycosylated alpha-subunit of beta- hexosaminidase undergoes an altered folding pathway resulting in the formation of an insoluble, inappropriately disulfide-bonded aggregate that is retained in the ER. The inappropriately folded protein is bound to BiP/GRP 70 which acts as a molecular scaffold in ER.