High impact information on ph-p

• Here we describe the characterization of a Bmi binding protein Mph1, which shares similarity to Drosophila polyhomeotic [1].
• Polycomb and polyhomeotic are constituents of a multimeric protein complex in chromatin of Drosophila melanogaster [2].
• In addition, by double-immunofluorescence labelling we can demonstrate that Polycomb and polyhomeotic have exactly the same binding patterns on polytene chromosomes of larval salivary glands [2].
• Chromosome 2 PH reveals additional alpha-heterochromatin [3].
• Furthermore, Polyhomeotic and Posterior Sex Combs are also associated with expressed genes [4].

Biological context of ph-p

• Our data show that PC and PH often bind to clustered regions within large loci that encode transcription factors which play multiple roles in developmental patterning and in the regulation of cell proliferation [5].
• The Drosophila Polycomb group gene Sex comb on midleg (Scm) encodes a zinc finger protein with similarity to polyhomeotic protein [6].
• In the corresponding larval imaginal discs, a polyhomeotic-lacZ enhancer trap is not normally activated in anterior cells adjacent to the anterior-posterior boundary [7].
• Employing similar gene identification and transfection techniques and subsequent biochemical analysis of the expressed enzymatic activity, we report the identity of the Drosophila gene phantom (phm), located at 17D1 of the X chromosome, as encoding the microsomal 25-hydroxylase (Cyp306a1) [8].
• Phenotypes of 33 mutations representing nine adjacent complementation groups including eight recessive lethals and one visible homeotic mutation (polyhomeotic) are described [9].

Anatomical context of ph-p

• Targeted disruption of the mouse homologue of the Drosophila polyhomeotic gene leads to altered anteroposterior patterning and neural crest defects [10].

Associations of ph-p with chemical compounds

• We also found that Drosophila Cyp306a1 is disrupted in the phantom (phm) mutant, known also as the Halloween mutant [11].

Other interactions of ph-p

• We show that the chromodomain of Polycomb is necessary for protein-protein interactions within a Polycomb-Polyhomeotic complex [4].
• Several arguments show that engrailed is responsible for the induction of polyhomeotic in these cells [7].

Analytical, diagnostic and therapeutic context of ph-p

• Using immunoprecipitation we show that two members of the Pc-G, Polycomb and polyhomeotic, are constituents of a soluble multimeric protein complex [2].
• The specimen consisted of a polytene chromosome spread from Drosophila melanogaster doubly labelled for the Polyhomeotic protein by indirect immunofluorescence labelling with Alexa594 and for DNA with YOYO-1 [12].

References