The recombinant lentiviral vectors expressing a luciferase reporter gene were produced as previously described [28, 54, 55] . To produce H5N1 pseudotyped viruses, 293T cells [45, 46] (5610 6 cells plated the day before) were transfected with 13.43 mg of pNL 4-3.Luc.R-E-(NIH AIDS reference and reagent program), 1.2 mg of H5-HA-wt DNA vaccine plasmid and 0.3 mg of N1-NA plasmid using 75 mg of polyetheleneimine transfection reagent. Supernatants were harvested 48 hours later, frozen at 280uC and then standardized by infectivity in 293A cells using a luciferase-based TCID50 measurement. For neutralization assays, serum samples (5 ml) were heat inactivated at 56uC for 30 minutes, then threefold serially diluted in culture medium in flat-bottomed microtiter plates. Pseudotyped H5N1 virions were then added to the plates at 200 TCID50/well and incubated for 1 hour at 37uC. After incubation, 293A cells were trypsinized and added to each plate at a dilution of 1610 4 cells per well. Following a 48-hour incubation, plates were developed using a luciferase assay system (Promega). Values averaged from triplicate wells were then used to determine IC50 based on wells that displayed 50% reduction in infection as compared to control wells containing virus plus pre-immune sera.  ELM—the database of eukaryotic linear motifs Linear motifs are short, evolutionarily plastic components of regulatory proteins and provide low-affinity interaction interfaces. These compact modules play central roles in mediating every aspect of the regulatory functionality of the cell. They are particularly prominent in mediating cell signaling, controlling protein turnover and directing protein localization. Given their importance, our understanding of motifs is surprisingly limited, largely as a result of the difficulty of discovery, both experimentally and computationally. The Eukaryotic Linear Motif (ELM) resource at http://elm.eu.org provides the biological community with a comprehensive database of known experimentally validated motifs, and an exploratory tool to discover putative linear motifs in user-submitted protein sequences. The current update of the ELM database comprises 1800 annotated motif instances representing 170 distinct functional classes, including approximately 500 novel instances and 24 novel classes. Several older motif class entries have been also revisited, improving annotation and adding novel instances. Furthermore, addition of full-text search capabilities, an enhanced interface and simplified batch download has improved the overall accessibility of the ELM data. The motif discovery portion of the ELM resource has added conservation, and structural attributes have been incorporated to aid users to discriminate biologically relevant motifs from stochastically occurring non-functional instances. Short linear motifs (SLiMs, LMs or MiniMotifs) are regulatory protein modules characterized by their compact interaction interfaces (the affinity and specificity determining residues are usually encoded between 3 and 11 contiguous amino acids (1)) and their enrichment in natively unstructured, or disordered, regions of proteins (2) . As a result of limited intermolecular contacts with their interaction partners, SLiMs bind with relatively *To whom correspondence should be addressed. Tel: +49 (0) 6221 3878398; Fax: +49 (0) 6221 387517; Email: gibson@embl-heidelberg.de low affinity (in the low-micromolar range), an advantageous attribute for use as transient, conditional and tunable interactions necessary for many regulatory processes. Due to the limited number of mutations necessary for the genesis of a novel motif, SLiMs are amenable to convergent evolution, functioning as a driver of network evolution by adding novel interaction interfaces, and thereby new functionality, to proteins. This evolutionary plasticity facilitates the rapid proliferation within a proteome, and as a result, motif use is ubiquitous in higher eukaryotes.