Chemical tools

Phosphorylation-driven protein-protein interactions: a protein kinase sensing system

Fluorescent probes are promising tools for the monitoring of kinase activity, but there remains a need for generalized strategies that can be applied to generate indicators for virtually any specific kinase. Wang and Lawrence describe such a strategy for probe design, an approach they believe could be used to prepare orthogonal probes for the simultaneous monitoring of several different kinases.

Wang, Q. & Lawrence, D.S. J. Am. Chem. Soc. 127, 7684–7685 (2005).

Protein biochemistry

Dissociation of ligand-receptor complexes using magnetic tweezers

Danilowicz et al. describe an inventive way to measure dissociation constants for ligand-receptor pairs. Receptors immobilized onto superparamagnetic beads are allowed to bind to their counterpart ligands, which have been adsorbed to a flat surface. Measurement of the force needed to magnetically separate the pairs permits accurate determination of dissociation kinetics.

Danilowicz, C. et al. Anal. Chem. 77, 3023–3028 (2005).

Proteomics

Global topology analysis of the Escherichia coli inner membrane proteome

Membrane proteins comprise a large percentage of the proteome but remain notoriously difficult to characterize. Daley et al. used two specialized reporter proteins to reveal the localization of the C termini for over 600 E. coli inner membrane proteins; with further computational analysis, this data allowed them to confidently determine the topology for each of these proteins.

Daley, D.O. et al. Science 308, 1321–1323 (2005).

Genomics

Clustering and conservation patterns of human microRNAs

Altuvia et al. performed a detailed clustering analysis of more than 200 known human microRNAs, and found that miRNA genes tend to have significantly greater clustering than would be expected at random. Via sequence analysis, the group was then able to identify and confirm the existence of 18 additional, new human miRNA genes within or near these clusters.

Altuvia, Y. et al. Nucleic Acids Res. 33, 2697–2706 (2005).

RNA interference

Antibody-mediated in vivo delivery of small interfering RNAs via cell-surface receptors

A primary obstacle to the therapeutic application of RNAi is in actually getting small inhibitory RNAs (siRNAs) into target cells. Song et al. show that by conjugating siRNAs to protamine-fused antibody Fab fragments, one can achieve efficient targeted gene inhibition in HIV-infected or cancer cells.

Song, E. et al. Nat. Biotechnol.; published online 22 May 2005.