Nucleocytoplasmic Transport, edited by R. Peters & M. Trendelenberg. Springer-Verlag, 1986. Pp. ix + 300. Dm 98
Based on the proceedings of a workshop on nucleocyto-plasmic transport held in Heidelberg in 1985, this collection of short papers aims to provide a brief but complete picture of the field and its prospects. To a large extent the editors have been successful in their task and have produced a book that would be very suitable for researchers familiar with the techniques of molecular cell biology to bring themselves reasonably up to date with recent developments in nucleo-cyto-plasmic transport.
As a prelude to recent work Brachet provides a charming historical perspective that summarizes early evidence for the structure of the nuclear envelope, its permeability to small solutes, RNA export from the nucleus and import of nuclear proteins from the cytoplasm. Unfortunately, seminal experiments performed in the 1970s, which established the concept of the nuclear envelope as a molecular filter that can selectively transport macromolecules, are not formally described anywhere in the text. Instead, we move directly to recent work encompassing methods that could be applied to study transport, the structure of the envelope, nuclear protein import and RNA transport.
By far the most successful aspect of the book is the treatment of nuclear protein import. Several good chapters review the data identifying targeting signals in nuclear proteins, including nucleoplasmin and SV40 virus large T antigen. These also include very recent data that establish important points: namely, that a polypeptide chain may contain more than one signal, multiple signals may enhance the rate of transport, and the position of a signal within a folded protein may be important in its function. In addition, evidence is also presented for signals specifying nuclear accumulation and matrix-binding, as well as the intriguing possibility that some proteins might migrate into the nucleus only after post-translational modification. While treatment of protein import is, on the whole, thorough and up to date, this field is progressing so rapidly that a number of important recent studies are not covered. These include the use of synthetic signal peptides to target reporter proteins, in vitro systems to study protein import, and a hormone-induced signal in the glucocor-ticoid receptor. The two chapters devoted to this receptor are actually irrelevant to the subject of the book.
RNA transport across the nuclear envelope is a much less well understood topic and is covered in this book only as snRNP import during early development, and electron-microscopic structural analysis of Balbiani ring ribonucleoproteins. Both are fascinating systems, but I feel that the book would have benefited from inclusion of work on tRNA export in Xenopus oocytes and, perhaps, one of the in vitro systems to study ATP-dependent RNA release from isolated nuclei.
Although there is a nice chapter on the structure of the pore complex by electron diffraction, on the whole coverage of the structure of the envelope is too brief. It deals too much with details and fails to provide a basic picture of the composition of this structure. I would have preferred to forgo the numerous chapters on methods in favour of more extensive treatment of this subject. Again, this aspect of the book suffers from being too premature to include the important recent finding that the lamins are intermediate filament-type proteins, and identification of several pore-complex proteins.
In summary, while this book may lack sufficient background information to be useful to a total newcomer to the subject, it gives a good overview of recent developments for those with a basic understanding of nuclear envelope structure and function. Particularly, it covers transport of proteins into the nucleus quite thoroughly in a way that would be most useful to researchers considering moving into the field or those looking for a general update on the topic.
Dr Featherstone works in the Department of Cell Biology & Anatomy, Johns Hopkins University School of Medicine
