The L63 gene is necessary for the ecdysone-induced 63E late puff and encodes CDK proteins required for Drosophila development.
The pulse of ecdysone that triggers Drosophila metamorphosis activates six early genes in a primary response made visible by polytene chromosome puffs. The secondary response is detected by the induction of over 100 late puffs, only a few of which have been subject to molecular genetic analysis. We present a molecular and mutational analysis of the L63 gene responsible for the late puff at 63E. This gene contains overlapping L63A, B, and C transcription units of which the A unit encodes two isoforms and the B unit three. The C unit, which exhibits little activity, encodes one of the B isoforms. Evidence that L63B, but not L63A, transcription is ecdysone responsive derives from their developmental transcription profiles and from P-element mutagenesis showing that ecdysone induction of the 63E puff requires sequences adjacent to the 5' end of L63B but not those adjacent to the 5' end of L63A. L63-specific lethal mutations showed that L63 is required not only for metamorphosis, but also maternally and for embryonic and larval development. The L63 proteins contain a common C-terminal 294-aa sequence that is 71% identical to the CDK sequence of the murine PFTAIRE protein. In vivo tests of L63 proteins altered by site-directed mutagenesis showed that they exhibit CDK functions. L63 proteins are widely distributed among late larval and prepupal tissues and are unlikely to be involved in cell cycle functions.
Stowers
R S
RS
Department of Biochemistry, Stanford University School of Medicine, Beckman Center, B300, Stanford, California 94305-5329, USA.
Garza
D
D
Rascle
A
A
Hogness
D S
DS
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle; D002874:Chromosome Mapping; D018244:Chromosomes, Artificial, Yeast; D003001:Cloning, Molecular; D018844:Cyclin-Dependent Kinases / Q000737:chemistry / Q000235:genetics*; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins; D004440:Ecdysone / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D011494:Protein Kinases / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*
D029721:Drosophila Proteins; D019476:Insect Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D004440:Ecdysone; D011494:Protein Kinases; D018844:Cyclin-Dependent Kinases; C408322:Eip63E protein, Drosophila