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Analysis of protein products encoded by the polyhomeotic locus, a member of the polycomb-group of genes in drosophila melanogaster DeCamillis, Mark Andrew
Abstract
Polyhomeotic (ph) belongs to the Polycomb-Group (PcG) of genes in Drosophila melanogaster. 12 PcG genes have so far been described, originally identified as trans-regulatory repressors of homeotic gene expression. PcG genes interact in multiple heterozygous combinations to mutually enhance gain of function homeotic phenotypes. In addition to homeotic effects, many PcG genes including ph exhibit pleiotropic phenotypes. Two models have been proposed to explain PcG interactions and function: 1) PcG genes form a hierarchical regulatory network which functions to elaborate the correct expression of a subset of members required at specific regulatory targets; 2) PcG members constitute single components of a multimeric protein complex that functions at specific regulatory targets. To further the molecular characterization of ph protein products and better understand its role in the PcG, I have produced a mono-specific polyclonal antiserum to ph proteins. Using this reagent I show that at least 4 distinct ph protein products are produced that are differentially expressed during development. Several correlations between ph phenotypes and ph protein expression are made. As expected from conceptual translation of a ph cDNA, I show that ph proteins are localized in the nucleus. Further analysis shows that ph is a chromatin binding protein that recognizes 80 specific sites on the polytene chromosome including locations of the homeotic gene complexes and several PcG genes. Comparison of ph and. Polycomb binding sites show a striking degree of overlap in which 71 of 80 ph sites are indistinguishable from Pc sites. I show that ph recognizes ectopically located bxd sequences (an upstream regulatory element in the Ubx gene of the bithorax complex) also recognized by Pc, indicating that ph localization is sequence dependent. Co-localization of ph and Pc throughout the genome and at bxd sequences suggest that these proteins either interact directly or function in close proximity at similar target genes. Co-immunoprecipitation experiments done on nuclear extracts show that ph and Pc proteins are present in the same irnmunoprecipitates, providing the first evidence that they associate in a multimeric complex.
Item Metadata
Title |
Analysis of protein products encoded by the polyhomeotic locus, a member of the polycomb-group of genes in drosophila melanogaster
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1992
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Description |
Polyhomeotic (ph) belongs to the Polycomb-Group (PcG) of
genes in Drosophila melanogaster. 12 PcG genes have so far been
described, originally identified as trans-regulatory repressors
of homeotic gene expression. PcG genes interact in multiple
heterozygous combinations to mutually enhance gain of function
homeotic phenotypes. In addition to homeotic effects, many PcG
genes including ph exhibit pleiotropic phenotypes. Two models
have been proposed to explain PcG interactions and function: 1)
PcG genes form a hierarchical regulatory network which functions
to elaborate the correct expression of a subset of members
required at specific regulatory targets; 2) PcG members
constitute single components of a multimeric protein complex that
functions at specific regulatory targets.
To further the molecular characterization of ph protein
products and better understand its role in the PcG, I have
produced a mono-specific polyclonal antiserum to ph proteins.
Using this reagent I show that at least 4 distinct ph protein
products are produced that are differentially expressed during
development. Several correlations between ph phenotypes and ph
protein expression are made.
As expected from conceptual translation of a ph cDNA, I show
that ph proteins are localized in the nucleus. Further analysis
shows that ph is a chromatin binding protein that recognizes 80
specific sites on the polytene chromosome including locations of
the homeotic gene complexes and several PcG genes. Comparison of
ph and. Polycomb binding sites show a striking degree of overlap
in which 71 of 80 ph sites are indistinguishable from Pc sites.
I show that ph recognizes ectopically located bxd sequences (an
upstream regulatory element in the Ubx gene of the bithorax
complex) also recognized by Pc, indicating that ph localization
is sequence dependent.
Co-localization of ph and Pc throughout the genome and at
bxd sequences suggest that these proteins either interact
directly or function in close proximity at similar target genes.
Co-immunoprecipitation experiments done on nuclear extracts show
that ph and Pc proteins are present in the same
irnmunoprecipitates, providing the first evidence that they
associate in a multimeric complex.
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Extent |
2520125 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2008-12-19
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0086638
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1992-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.