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MINIREVIEW

The social life of ribosomal proteins

Ditlev E. Brodersen and Poul Nissen

Centre for Structural Biology, Department of Molecular Biology, University of Aarhus, Denmark

Introduction

Ribosomes are complex macromolecular machines that

are responsible for the production of every protein in

every living cell [1]. Ribosomes are themselves built

from the very molecules of life; protein and RNA, and

ribosomal composition and structure and the inter￾action between the two types of building blocks within

them have always fascinated researchers. In recent lit￾erature there has been renewed focus on rRNA as the

main, and perhaps only, catalyst in the ribosome – a

development which in the minds of many in the field

has left ribosomal proteins in the dark as ‘merely glue’.

In this review we highlight some of the many import￾ant biological roles of ribosomal proteins, apart from

being ‘RNA-glue’, and show that they indeed seem to

have a social life after all.

Until the year 2000, ribosomal protein structure and

interaction with rRNA were mainly studied in a ‘dissect￾ing’ fashion, focusing on each individual protein in turn

[2]. Many individual protein structures were determined

in isolation and their interactions with rRNA were

mapped by various biochemical techniques, such as hyd￾roxy-radical probing, protein footprinting, mutational

analysis and cross-linking [3]. Though these experiments

created a wealth of useful information about the struc￾tural and functional organization of the ribosome, the

information was very ‘local’ in the sense that it focused

on the close surroundings of each ribosomal protein.

The overall structure and inner workings of the ribo￾some therefore remained elusive.

A unified understanding of the ribosome was not

possible until complete atomic structures of the two

subunits that make up the bacterial 70S ribosome, the

50S and 30S subunits, were published in the summer

of 2000 (Fig. 1) [4–6]. Not only did these structures

(1.5 MDa and 850 kDa, respectively) represent the lar￾gest nonsymmetric crystal structures ever determined,

they also increased the size of the nucleic acid database

(NDB; http://ndbserver.rutgers.edu/) by several orders

of magnitude. The structures contained nothing short

of a goldmine of information about RNA structure

and immediately suggested several important new

RNA folds and rationales of RNA tertiary and quater￾nary structure that had not hitherto been appreciated

[5,7,8]. A wealth of new information about protein–

RNA interactions was likewise deduced from analysis

of the 50 or more proteins in the two subunits, in a

Keywords

crystallography; protein synthesis; ribosomal

proteins structure; ribosome; rRNA;

translation

Correspondence

D. E. Brodersen or P. Nissen, Centre for

Structural Biology, Department of Molecular

Biology, University of Aarhus, Gustav Wieds

Vej 10c, DK-8000 A˚ rhus C, Denmark

E-mail: [email protected] or [email protected]

(Received 25 January 2005, accepted

7 March 2005)

doi:10.1111/j.1742-4658.2005.04651.x

Ribosomal proteins hold a unique position in biology because their func￾tion is so closely tied to the large rRNAs of the ribosomes in all kingdoms

of life. Following the determination of the complete crystal structures of

both the large and small ribosomal subunits from bacteria, the functional

role of the proteins has often been overlooked when focusing on rRNAs as

the catalysts of translation. In this review we highlight some of the many

known and important functions of ribosomal proteins, both during trans￾lation on the ribosome and in a wider context.

Abbreviations

EF-Tu, elongation factor Tu; hnRNP, heteronuclear ribonucleoparticle; IF1, initiation factor 1; IRES, internal ribosome entry site; OB-fold,

oligonucleotide-binding fold; PNPase, polynucleotide phosphorylase; RACK1, receptor of activated C kinase; SRP, signal recognition particle.

2098 FEBS Journal 272 (2005) 2098–2108 ª 2005 FEBS