The Drosophila SSL gene is expressed in larvae, pupae, and adults, exhibits sexual dimorphism, and mimics properties of the beta subunit of casein kinase II.
Drosophila melanogaster casein kinase II (CKII) is composed of catalytic alpha and regulatory beta subunits that generate the alpha2beta2 holoenzyme. A two-hybrid screen of a Drosophila embryo library using CKIIalpha as bait has resulted in the isolation of multiple cDNAs encoding SSL, a CKIIbeta-like polypeptide. We demonstrate that CKIIbeta, beta', and SSL exhibit robust and comparable interaction with CKIIalpha. Residues in SSL that mediate interaction with CKIIalpha appear similar to those in CKIIbeta, and SSL forms homodimers and heterodimers with CKIIbeta or beta' as well. We have tested all known Drosophila CKIIbeta-like proteins for rescue of the ion-homeostasis defect of yeast lacking beta subunits and find that CKIIbeta and SSL complement, beta' has marginal function, and Stellate appears non-functional. We have used real-time RT-PCR to assess developmental expression, and find that CKIIbeta is robust and ubiquitous, whereas SSL is restricted to males (third-instar-larvae, pupae, and adults), but is nondetectable in females of the corresponding stages. These results indicate that SSL expression encompasses a greater developmental window than that previously suggested and may confer distinct functions to CKII in a sex-specific manner.
Karandikar
Umesh
U
Department of Biology, Life Sciences Building, West Virginia University, P.O. Box 6057, Morgantown, WV 26506-6057, USA.
Anderson
Stacey
S
Mason
Neil
N
Trott
Regina L
RL
Bishop
Clifton P
CP
Bidwai
Ashok P
AP
D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D017344:Genes, Insect; D007814:Larva / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics*; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D011679:Pupa / Q000201:enzymology; D012097:Repressor Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012727:Sex Characteristics; D020798:Two-Hybrid System Techniques
D018076:DNA, Complementary; D029721:Drosophila Proteins; D021122:Protein Subunits; D012097:Repressor Proteins; C106547:Ssl protein, Drosophila; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases