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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

South-western screening of lambda gt11 expression library with a fragment of the Shrunken promoter containing the initiator element resulted in cloning of a novel maize gene. The encoded initiator-binding protein (IBP1) interacts at the transcription start site of the Shrunken promoter. Analysis of the 680 amino acid (aa) long polypeptide revealed a novel bipartite DNA-binding domain at the carboxyl terminus. In its amino-terminal part, it is weakly related to Myb R-repeats but the following basic region is also essential for DNA binding. A region of similarity to the conserved 2.1 and 2.2 motifs in bacterial sigma-factors is located close to the IBP1 amino terminus. Two putative nuclear localization signals are compatible with the presence of antigenically related polypeptides in nuclear protein extracts. The IBP1 gene was mapped to the long arm of chromosome 9 (9L095); a second highly related gene IBP2 is located on the short arm of chromosome 1 (1S014). Both genes encode proteins sharing 93% similarity and are transcribed with similar activity in different plant organs. A small 82 nucleotide intron in the IBP2 transcript is found unspliced to a variable degree in different tissues. Translation of this incompletely processed transcript would result in a truncated amino-terminal polypeptide lacking the DNA-binding domain.
Plant Mol Biol 1994 Jun
PMID:A novel DNA-binding domain in the Shrunken initiator-binding protein (IBP1). 791 1

The transcription start site of the maize Shrunken-1 (Sh-1) gene is sufficient for transcriptional initiation in the absence of other promoter elements and is recognized in vitro by the Initiator Binding Protein (IBP). We describe here in situ hybridization experiments performed on various maize tissues to quantify IBP transcription at the cellular level. IBP transcripts are found in the endosperm and in differentiating, enlarging cells of the shoot and the root of the maize seedling. This expression pattern overlaps with that of the Sh-1 gene and is therefore compatible with the hypothesis that the Sh-1 transcription start site is a target for IBP. In the developing spikelets of male and female inflorescences IBP transcript levels are very high in those organs that are later aborted when flowers become unisexual. Overexpression of the maize IBP1 gene product in transgenic tobacco causes a reduction in internodal elongation and effects gibberellin hormonal balance. The cellular expression pattern described here establishes IBP transcripts as an interesting molecular marker for enlarging, and presumably differentiating, cells released from the root or shoot apex.
Mol Gen Genet 1997 Jul
PMID:The IBP genes of maize are expressed in non-meristematic, elongating cells of the seedling and in abortive floral organs. 926 15