Molecular cloning of polybromo, a nuclear protein containing multiple domains including five bromodomains, a truncated HMG-box, and two repeats of a novel domain

• Published in: Gene Vol. 175; no. 1; pp. 233 - 240
• Main Authors: Nicolas, Robert H., Goodwin, Graham H.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.10.1996
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Brahma; Cells, Cultured; Chick Embryo; Chickens; Cloning, Molecular; DNA, Complementary - genetics; Methyltransferase; Methyltransferases - genetics; Molecular Sequence Data; Nuclear Proteins - genetics; Promoter Regions, Genetic - genetics; Repetitive Sequences, Nucleic Acid; SNF2; Transcription Factors - genetics; SNF2; PB; HMG; DMTase; Methyltransferase; Brahma; BAH; GST
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/0378-1119(96)82845-9

A number of transcription factors that act as adaptor proteins have been found to contain an 87 amino acid domain called the bromodomain. In a study to identify and characterise bromodomain proteins expressed in chicken cells, a novel gene has been isolated which encodes five repeats of the bromodomain. In addition, the encoded protein, termed polybromo, contains four other domains: an unusual truncated HMG box, two repeats of a novel domain which we term the BAH domain and a sequence related to a region within the regulatory domain of the DNA cytosine-5 methyltransferase enzyme. Polybromo was found to be related to a yeast protein U19102 which has two bromo domains, a BAH domain and the DNA methyltransferase-related sequence. Antibodies that were raised against polybromo were used in confocal microscopy analysis to show that the 180-kDa polybromo protein is located within the nucleus but excluded from the nucleolus. Gel filtration analysis of nuclear extracts demonstrate that polybromo is part of a large complex with a mass of approximately 2 million dalton.