Auth D, Brawerman G
Department of Biochemistry, Tufts University Health Sciences Campus, Boston, MA 02111.
Proc Natl Acad Sci U S A. 1992 May 15;89(10):4368-72. doi: 10.1073/pnas.89.10.4368.
A 33-kDa polypeptide (termed p40), which shares an antigenic determinant with a laminin receptor and is under translational control, is believed to serve as a precursor to the receptor and to be related to the neoplastic state. The present study of subcellular localization of this protein shows it to be a cytoplasmic component not associated with the plasma membrane. Most of the cellular p40 was found to be associated with polyribosomes as well as with 40S to 60S cytoplasmic particles. Conditions that lead to polysome disruption also caused release of the polysomal form of p40 as smaller particles, and polysome reconstitution was accompanied by uptake of p40 into these structures. Because of the large abundance of this protein in the cells (six to eight copies per ribosome), it is unlikely that it represents a factor that associates with the 40S preinitiation complex. The p40-containing particles appear to represent a newly discovered structure involved in the process of polysome formation.
一种33 kDa的多肽（称为p40），它与层粘连蛋白受体共享一个抗原决定簇，且处于翻译控制之下，被认为是该受体的前体并与肿瘤状态相关。对这种蛋白质的亚细胞定位的当前研究表明它是一种不与质膜相关的细胞质成分。发现大多数细胞中的p40与多核糖体以及40S至60S的细胞质颗粒相关。导致多核糖体破坏的条件也会使p40的多核糖体形式以较小颗粒的形式释放，并且多核糖体的重建伴随着p40被摄取到这些结构中。由于这种蛋白质在细胞中含量丰富（每个核糖体有六到八个拷贝），它不太可能代表与40S起始前复合物相关的因子。含p40的颗粒似乎代表了一种新发现的参与多核糖体形成过程的结构。
