Ribosomal s6 kinase cooperates with casein kinase 2 to modulate the Drosophila circadian molecular oscillator.

There is a universal requirement for post-translational regulatory mechanisms in circadian clock systems. Previous work in Drosophila has identified several kinases, phosphatases, and an E3 ligase that are critical for determining the nuclear translocation and/or stability of clock proteins. The present study evaluated the function of p90 ribosomal S6 kinase (RSK) in the Drosophila circadian system.

CK2beta interacts with and regulates p21-activated kinases in Drosophila.

The role of CK2beta has been defined as the regulatory subunit of protein kinase CK2, which is a heterotetrameric complex composed of two CK2beta and two catalytic active CK2alpha subunits. The identification of other serine/threonine kinases such as A-Raf, Chk1, and c-Mos that interact with and are regulated by CK2beta has challenged this view and provided evidence for functions of CK2beta outside the CK2 holoenzyme. In this report we describe the first interaction of Drosophila CK2beta outside the CK2 holoenzyme with p21-activated kinase (PAK) proteins.

The Drosophila melanogaster DmCK2beta transcription unit encodes for functionally non-redundant protein isoforms.

Genes encoding for the two evolutionary highly conserved subunits of a heterotetrameric protein kinase CK2 holoenzyme are present in all examined eukaryotic genomes. Depending on the organism, multiple transcription units encoding for a catalytically active CK2alpha subunit and/or a regulatory CK2beta subunit may exist. The phosphotransferase activity of members of the protein kinase CK2alpha family is thought to be independent of second messengers but is modulated by interaction with CK2beta-like proteins.

A role for CK2 in the Drosophila circadian oscillator.

The posttranslational modification of clock proteins is critical for the function of circadian oscillators. By genetic analysis of a Drosophila melanogaster circadian clock mutant known as Andante, which has abnormally long circadian periods, we show that casein kinase 2 (CK2) has a role in determining period length. Andante is a mutation of the gene encoding the beta subunit of CK2 and is predicted to perturb CK2beta subunit dimerization.

In vivo functional analysis of Drosophila protein kinase casein kinase 2 (CK2) beta-subunit.

Protein casein kinase 2 (CK2) is a heterotetramer composed of two catalytic (alpha) and two regulatory (beta) subunits. In Drosophila melanogaster, four genes encoding for one CK2alpha (DmCK2alpha) and three CK2beta (DmCK2beta, DmCK2beta' and DmCK2betates) subunits have been identified. Here, we have focused on the role of DmCK2beta.