Multiple adenosine 3',5'-cyclic [corrected] monophosphate response element DNA-binding proteins generated by gene diversification and alternative exon splicing.
The protein sequence deduced from the open reading frame of a human placental cDNA encoding a cAMP-responsive enhancer (CRE)-binding protein (CREB-327) has structural features characteristic of several other transcriptional transactivator proteins including jun, fos, C/EBP, myc, and CRE-BP1. Results of Southwestern analysis of nuclear extracts from several different cell lines show that there are multiple CRE-binding proteins, which vary in size in cell lines derived from different tissues and animal species. To examine the molecular diversity of CREB-327 and related proteins at the nucleic acid level, we used labeled cDNAs from human placenta that encode two different CRE-binding proteins (CREB-327 and CRE-BP1) to probe Northern and Southern blots. Both probes hybridized to multiple fragments on Southern blots of genomic DNA from various species. Alternatively, when a human placental c-jun probe was hybridized to the same blot, a single fragment was detected in most cases, consistent with the intronless nature of the human c-jun gene. The CREB-327 probe hybridized to multiple mRNAs, derived from human placenta, ranging in size from 2-9 kilobases. In contrast, the CRE-BP1 probe identified a single 4-kilobase mRNA. Sequence analyses of several overlapping human genomic cosmid clones containing CREB-327 sequences in conjunction with polymerase chain reaction indicates that the CREB-327/341 cDNAs are composed of at least eight or nine exons, and analyses of human placental cDNAs provide direct evidence for at least one alternatively spliced exon. Analyses of mouse/hamster-human hybridoma DNAs by Southern blotting and polymerase chain reaction localizes the CREB-327/341 gene to human chromosome 2. The results indicate that there is a dichotomy of CREB-like proteins, those that are related by overall structure and DNA-binding specificity as well as those that are related by close similarities of primary sequences.
Hoeffler
J P
JP
Massachusetts General Hospital, Howard Hughes Medical Institute, Harvard Medical School, Boston 02114.
Meyer
T E
TE
Waeber
G
G
Habener
J F
JF
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D002889:Chromosomes, Human, Pair 2; D017362:Cyclic AMP Response Element-Binding Protein; D004247:DNA / Q000032:analysis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005091:Exons; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000235:genetics
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D012333:RNA, Messenger; D004247:DNA