BIOLOGICAL CHARACTERIZATION OF VARIOUS FORMS OF ELONGATION FACTOR-I FROM RABBIT RETICULOCYTES
BIOLOGICAL CHARACTERIZATION OF VARIOUS FORMS OF ELONGATION FACTOR-I FROM RABBIT RETICULOCYTES
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DOI：
10.1016/0003-9861(84)90310-2
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发表时间：
1984-01-01
影响因子：
3.9
通讯作者：
MERRICK, WC
中科院分区：
文献类型：
--
作者：
CARVALHO, MDD;CARVALHO, JF;MERRICK, WC
两种形式的延伸因子1（EF-1）已被测试的各种生物功能。一种形式EF-1H是含有四种不同多肽（α、β、γ、δ）的高分子量聚集体（Mr> 500，000）。另一种形式EF-1α由与EF-1H的α亚基相同的单一多肽组成。EF-1α和EF-1H在Phe-tRNA与核糖体的结合和poly（U）-指导的聚苯丙氨酸合成中均具有催化作用。EF-1α的活性在聚苯丙氨酸合成中通过互补组分EF-1βδ增强。还表明EF-1βδ可以促进EF-1α结合的GDP与GTP的交换。EF-1α对GDP和GTP的解离常数分别为0.47和0.55 μ m，EF-1H对GDP和GTP的解离常数分别为2.0和1.6 μm。因此，虽然EF-1α和EF-1H对GDP和GTP的亲和力大致相同，但EF-1α的解离常数比EF-1H的解离常数低约四倍。尝试使用Millipore过滤器、凝胶过滤或蔗糖密度梯度分离EF-1α或EF-1H与GTP和Phe-tRNA或与GTP、Phe-tRNA和核糖体的复合物均未成功。本报告中的结果，沿着其他实验室的研究，加强了真核生物和原核生物延长周期的一般机制相似的假设。
Two forms of elongation factor 1 (EF-1) have been tested for a variety of biological functions. One form, EF-1H, is a high-molecular-weight aggregate (Mr> 500,000) containing four distinct polypeptides (α, β, γ, δ). The other form, EF-1α, consists of a single polypeptide which is the same as the α subunit of EF-1H. Both EF-1α and EF-1H function catalytically in binding Phe-tRNA to ribosomes, and in poly(U)-directed polyphenylalanine synthesis. The activity of EF-1α is enhanced in polyphenylalanine synthesis by a complementary component, EF-1βδ. It is also shown that EF-1βδ can facilitate an exchange of EF-1α-bound GDP for GTP. The EF-1α dissociation constants for GDP and GTP were 0.47 and 0.55 μmrespectively, while the EF-1H dissociation constants for GDP and GTP were 2.0 and 1.6 μm, respectively. Thus, while EF-1α and EF-1H had approximately the same affinities for GDP and GTP, the EF-1α dissociation constants were about fourfold lower than the EF-1H dissociation constants. Attempts to isolate complexes of EF-1α or EF-1H with GTP and Phe-tRNA or with GTP, Phe-tRNA, and ribosomes were unsuccessful using either Millipore filters, gel filtration, or sucrose density gradients. The results presented in this report, along with studies from other laboratories, strengthen the hypothesis that the general mechanism of the elongation cycle is similar in eucaryotes and procaryotes.