On the front covers of this month’s issue are from two HOT articles from Koby Levy and David Cowburn.
The article from Koby Levy and colleagues at Weizmann Institute of Science, Israel, addresses the origins of protein ubiquitination, a major regulatory mechanism involved in many important cellular pathways. They quantify the rates of evolutionary changes of ubiquitination and small ubiquitin-like modifier) sites, estimating when they first appeared and compare them to acetylation and phosphorylation sites and unmodified residues.
The origins and evolution of ubiquitination sites
Tzachi Hagai, Ágnes Tóth-Petróczy, Ariel Azia and Yaakov Levy
David Cowburn’s team from the Albert Einstein College of Medicine of Yeshiva University, USA, have devised a simple method to express and purify isolated Abl kinase domain and SH3–SH2–kinase multi-domain structures. Due to the involvement of tyrosine kinases in cell development, and the associated implications for development and cancer resulting from changes in kinase structures, tyrosine kinases are being targeted for molecular therapeutics. However, expressing tyrosine kinases as recombinant forms in bacterial systems for study has to date been a challenge. Cowburn et al’s method provides new avenues for structure–function studies, as the expressed Abl proteins retain correct folding and biological function, and segments can be isotopically labelled.
Abl kinase constructs expressed in bacteria: facilitation of structural and functional studies including segmental labeling by expressed protein ligation
Rong Xu, Dongsheng Liu and David Cowburn
As with all our cover articles, both of these are free to access (following a simple registration) for 6 weeks.