Diurnal protein oscillation profiles in Drosophila head.

Circadian clocks control daily rhythms in physiology, metabolism and behaviour in most organisms. Proteome-wide analysis of protein oscillations is still lacking in Drosophila. In this study, the total protein and phosphorylated protein in Drosophila heads in a 24-h daily time-course were assayed by using the isobaric tags for relative and absolute quantitation (iTRAQ) method, and 10 and 7 oscillating proteins as well as 19 and 22 oscillating phosphoproteins in the w1118 control and ClkJrk mutant strains were separately identified. Lastly, we performed a mini screen to investigate the functions of some oscillating proteins in circadian locomotion rhythms. This study provides the first proteomic profiling of diurnally oscillating proteins in fly heads, thereby providing a basis for further mechanistic studies of these proteins in circadian rhythm.