Multiple isoforms of GAGA factor, a critical component of chromatin structure.
The GAGA transcription factor of Drosophila melanogaster is ubiquitous and plays multiple roles. Characterization of cDNA clones and detection by domain- specific antibodies has revealed that the 70-90 kDa major GAGA species are encoded by two open reading frames producing GAGA factor proteins of 519 amino acids (GAGA-519) and 581 amino acids (GAGA-581), which share a common N-terminal region that is linked to two different glutamine-rich C-termini. Purified recombinant GAGA-519 and GAGA-581 proteins can form homomeric complexes that bind specifically to a single GAGA sequence in vitro. The two GAGA isoforms also function similarly in transient transactivation assays in tissue culture cells and in chromatin remodeling experiments in vitro . Only GAGA-519 protein accumulates during the first 6 h of embryogenesis. Thereafter, both GAGA proteins are present in nearly equal amounts throughout development; in larval salivary gland nuclei they colocalize completely to specific regions along the euchromatic arms of the polytene chromosomes. Coimmunoprecipitation of GAGA-519 and GAGA-581 from crude nuclear extracts and from mixtures of purified recombinant proteins, indicates direct interactions. We suggest that homomeric complexes of GAGA-519 may function during early embryogenesis; both homomeric and heteromeric complexes of GAGA-519 and GAGA-581 may function later.
Benyajati
C
C
Department of Biology, University of Rochester, Rochester, NY 14627, USA. tip@cb.biology.rochester.edu
Mueller
L
L
Xu
N
N
Pappano
M
M
Gao
J
J
Mosammaparast
M
M
Conklin
D
D
Granok
H
H
Craig
C
C
Elgin
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002843:Chromatin / Q000648:ultrastructure*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000737:chemistry*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009698:Nucleoproteins / Q000737:chemistry; D009707:Nucleosomes / Q000648:ultrastructure; D011485:Protein Binding; D014157:Transcription Factors / Q000737:chemistry*
D002843:Chromatin; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D009698:Nucleoproteins; D009707:Nucleosomes; D014157:Transcription Factors; C063460:Trl protein, Drosophila