Results and Problems in Cell Differentiation, Vol 33: Mammalian Carbohydrate Recognition Systems
Edited by Paul R. Crocker.
Springer-Verlag (2001) 252 pages. ISBN 3-540-67335-0
£68/$99.
Different sugar structures can be recognised by different carbohydrate-binding proteins (CBPs), some of which are called lectins. Although these proteins are involved in a diversity of recognition mechanisms, the lectins may be placed in categories based on their function, structure or primary amino acid sequence. Some of these categories may be divided into subfamilies that may be split again into subgroups. To get an overview can be difficult if you are not working at the centre of this field. Mammalian Carbohydrate Recognition Systems may help you develop such an overview.
The book consists of twelve chapters on CBPs written by experts in their respective fields. The short Preface written by the Editor indicates that CBPs fall into a handful of different categories: C-type lectins, galectins, I-type lectins, P-type lectins and legume-related lectins. In addition, the hyaluronic-acid-binding protein CD44 is classified as a ‘stand-alone’ CBP. At the start of every chapter one may wonder what category the CBP(s) in question belongs to. In some chapters this is clearly stated, while in others this information is more cryptic. It would have been very helpful to have an extended preface or a short general introduction with a table or map of the different categories, their members, and a few key words about their known specificity, function and distribution. It is also not completely obvious why the Editor claims that CD44 has to ‘stand alone’. Bajorath, the author of the chapter in question, states that CD44 belongs to the cartilage link protein family, with respect to the lectin domain. Although not mentioned in the book, the lecticans (aggrecan, versican, neurocan, brevican; see Iozzo, R. (1998) Annu. Rev. Biochem.67, 609-652) also contain link modules in addition to C-type lectin domains and are thus, like a few other proteins, able to bind hyaluronic acid.
A book consisting of chapters written by several authors may differ from a collection of individual reviews in some ways. First, a book should be written for those working outside the field, or studying rather than for the insiders in the field. Secondly, a book should be built in a logical way, where neighbouring chapters stimulate the reading of each other. In this book the journey starts inside the cell with the calcium and sugar-binding ER chaperones calnexin and calreticulin (Jakob et al.), and continues with the complex mannose-binding MR60/ERGIC-53 protein circulating between the ER, ERGIC and the Golgi apparatus (Roche and Monsigny), the cation-independent mannose-6-phosphate receptor (a P-type lectin) operating in the endocytic pathway (Kim and Dahms), and the fairly small galectins that are synthesised in the cytosol but may be found at many locations (Leffler). After these first four chapters the focus is more or less on cell surface molecules, such as CD44 (Bajorath), the macrophage mannose receptor (Taylor), the Man/GalNAc-4-SO4-receptor (Woodworth and Baenziger), sialoadhesin structure (May and Jones), Siglecs (Kelm), functions of selectins (Ley), ligands for selectins (Feizi) and collectins (Kishore and Reid). The chapters are all well written, although there is variability on how they are focussed. Some chapters focus on cell biology aspects, some on ligands and some on lectin structure. This may reflect state of the art in each area or the interests of the author(s). In addition, the chapters differ in the number of illustrations, from chapters with only one figure, to chapters well equipped with tables and figures.
All books published these days may raise questions important for the new millennium and/or for the post-genomic years. With the human genome sequence at hand, a complete overview of all human lectin genes may soon be available, even if quite similar C-type lectin domain 3D structures may have as little as 30% amino acid sequence similarity. The major effort in the future will probably be the definition of carbohydrate specificities, which cannot be read directly from structural data, how and where post-translational (in the case of the protein ligands) modifications are synthesised, and what the results of the lectin-ligand interactions are. In this respect, the chapters will bring the reader to the forefront of knowledge in the field; so, if you want to learn about mammalian carbohydrate recognition systems, this is a fine book to read.
