Reviews & Analysis

Biochemical studies on the spliceosomal helicase Brr2 reveal that it is activated by Prp8, the master regulator of the splicing cycle. Substitutions in Prp8 that cause retinal degeneration in humans block activation of Brr2, providing insight into the molecular pathology of retinitis pigmentosa.

Endonucleases have generally not been considered among the major factors in well-studied mRNA-decay and quality-control pathways in mammals and yeast. However, two important players in these pathways, the exosome and SMG6, have now been shown to contain functionally significant endonucleolytic activities.

The formation of heterochromatin involves spreading of repressor proteins along large chromosomal domains. A new study reveals that the concept of spreading also holds true for establishing domains of active chromatin. More specifically, spreading of the Drosophila melanogaster male-specific lethal (MSL) activator complex, which is required for dosage compensation on the X chromosome, involves interaction between the MSL3 chromodomain and histone H3 methylated at lysine 36.

Alternative splicing is typically thought to be controlled by RNA binding proteins that modulate the activity of the spliceosome. A new study not only demonstrates that alternative splicing can be regulated without the involvement of auxiliary splicing factors, but also provides mechanistic insight into how this can occur.

Hsp90s, molecular chaperones critically involved in many essential cellular processes, were the focus of a recent international conference held in Seeon, Germany. The scope of the conference ranged from structural and mechanistic insights all the way to medical applications.