title: Cloning of Mix-related homeodomain proteins using fast retrieval of gel shift activities, (FROGS), a technique for the isolation of DNA-binding proteins.
abstract: We have developed a technique, fast retrieval of gel shift activities (FROGS), that allows for the rapid isolation of proteins that interact with DNA. Using this technique, we have isolated two proteins that are structurally similar to Mix.1, a PAX class homeodomain protein with ventralizing activity in Xenopus. The Mix family of proteins are expressed during late blastula and gastrula stages of Xenopus development. During gastrulation, these genes are expressed at high levels in distinct, yet overlapping regions in mesoderm and endoderm. The members of the Mix family heterodimerize with each other and overexpression of each results in severe axial abnormalities. Mix.3 and Mix.4 can directly induce primitive ectoderm to become endoderm whereas Mix.1 cannot. Injection of Mix.3 or Mix.4 RNA in the whole embryo results in extensive ectopic endodermin mRNA expression. The expression of the Mix family homeoproteins is differentially regulated by activin, Vg1, BMP-4, and fibroblast growth factor, supporting a model in which the Mix homeoproteins are downstream effectors of growth factor signaling during endoderm and ventral mesoderm formation.
authors.affiliation: Department of Pediatrics, Division of Hematology/Oncology, Harvard Medical School, Children's Hospital, Enders 780, 300 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: P E
authors.initials: PE
authors.lastname: Mead
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.forename: K D
authors.initials: KD
authors.lastname: Lustig
authors.forename: T L
authors.initials: TL
authors.lastname: Huber
authors.forename: M W
authors.initials: MW
authors.lastname: Kirschner
authors.forename: L I
authors.initials: LI
authors.lastname: Zon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular / Q000379:methods*; D004268:DNA-Binding Proteins / Q000302:isolation & purification*; D019281:Dimerization; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006410:Hematopoiesis / Q000502:physiology; D018398:Homeodomain Proteins / Q000737:chemistry*; D017403:In Situ Hybridization; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins
chemical_list: D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C100368:Mix1 protein, Xenopus; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins