1b72 | pdb_00001b72
PBX1, HOMEOBOX PROTEIN HOX-B1/DNA TERNARY COMPLEX
Structural highlights
Disease[PBX1_HUMAN] Note=A chromosomal aberration involving PBX1 is a cause of pre-B-cell acute lymphoblastic leukemia (B-ALL). Translocation t(1;19)(q23;p13.3) with TCF3. TCF3-PBX1 transforms cells by constitutively activating transcription of genes regulated by PBX1 or by other members of the PBX protein family. [HXB1_HUMAN] Defects in HOXB1 are the cause of facial paresis, hereditary congenital, 3 (HCFP3) [MIM:614744]. A form of facial paresis, a disease characterized by isolated dysfunction of the facial nerve (CN VII). HCFP3 patients are affected by bilateral facial palsy, facial muscle weakness of muscles innervated by CN VII, hearing loss, and strabismus.[1] Function[PBX1_HUMAN] Binds the sequence 5'-ATCAATCAA-3'. Acts as a transcriptional activator of PF4 in complex with MEIS1. Converted into a potent transcriptional activator by the (1;19) translocation. May have a role in steroidogenesis and, subsequently, sexual development and differentiation. Isoform PBX1b as part of a PDX1:PBX1b:MEIS2b complex in pancreatic acinar cells is involved in the transcriptional activation of the ELA1 enhancer; the complex binds to the enhancer B element and cooperates with the transcription factor 1 complex (PTF1) bound to the enhancer A element. Probably in complex with MEIS2, is involved in transcriptional regulation by KLF4.[2] [3] [HXB1_HUMAN] Sequence-specific transcription factor which is part of a developmental regulatory system that provides cells with specific positional identities on the anterior-posterior axis. Acts on the anterior body structures. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHox homeodomain proteins are developmental regulators that determine body plan in a variety of organisms. A majority of the vertebrate Hox proteins bind DNA as heterodimers with the Pbx1 homeodomain protein. We report here the 2.35 A structure of a ternary complex containing a human HoxB1-Pbx1 heterodimer bound to DNA. Heterodimer contacts are mediated by the hexapeptide of HoxB1, which binds in a pocket in the Pbx1 protein formed in part by a three-amino acid insertion in the Pbx1 homeodomain. The Pbx1 DNA-binding domain is larger than the canonical homeodomain, containing an additional alpha helix that appears to contribute to binding of the HoxB1 hexapeptide and to stable binding of Pbx1 to DNA. The structure suggests a model for modulation of Hox DNA binding activity by Pbx1 and related proteins. Structure of a HoxB1-Pbx1 heterodimer bound to DNA: role of the hexapeptide and a fourth homeodomain helix in complex formation.,Piper DE, Batchelor AH, Chang CP, Cleary ML, Wolberger C Cell. 1999 Feb 19;96(4):587-97. PMID:10052460[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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