Department of Biology, University of California, San Diego, La Jolla, California 92093.
Plant Physiol. 1977 Mar;59(3):471-7. doi: 10.1104/pp.59.3.471.
The size classes of polyribosomes involved in the synthesis of ribulose-1,5-bisphosphate carboxylase large subunit were determined by binding radioiodinated specific antibodies to polyribosomal preparations from Chlamydomonas reinhardi. Antibodies specific to the denatured large subunit and to the native enzyme bound primarily to small polyribosomes (N = two to five ribosomes). The binding of antibodies to small polyribosomes was unexpected since the large subunit is a large polypeptide (molecular weight 55,000) coded for by a corresponding large mRNA (12-14S). Control experiments showed that this unexpected pattern of antibody binding was not a result of messenger RNA degradation, "run-off" of ribosomes from polyribosomes, or adventitious binding of the completed enzyme to a selected class of polyribosomes. In addition, polyribosomes bearing nascent large subunit chains have been immunoprecipitated from small polyribosome fractions. A large RNA species that can direct the synthesis of large subunit in vitro was extracted from small polyribosomes.
多核糖体的大小类别参与核酮糖-1,5-二磷酸羧化酶大亚基的合成，这是通过将放射性碘标记的特异性抗体结合到衣藻的多核糖体制剂中确定的。针对变性大亚基和天然酶的抗体主要与小多核糖体（N=2 到 5 个核糖体）结合。抗体与小多核糖体的结合是出乎意料的，因为大亚基是一个大的多肽（分子量 55000），由相应的大 mRNA（12-14S）编码。对照实验表明，这种意想不到的抗体结合模式不是信使 RNA 降解、核糖体从多核糖体上“跑出”或完整酶偶然结合到选定的多核糖体类别的结果。此外，从小多核糖体部分中免疫沉淀出带有新生大亚基链的多核糖体。从小多核糖体中提取了一种能够在体外指导大亚基合成的大 RNA 种类。
