Structure, chromosomal localization and evolutionary conservation of the gene encoding human U1 snRNP-specific A protein.
Three specific proteins, called A, 70K and C, are present in the U1 small nuclear ribonucleoprotein (snRNP) particle, in addition to the common proteins. The human U1 snRNP-specific A protein is, apart from a proline-rich region, highly similar to the U2 snRNP-specific protein B". To examine the homologous regions at the genomic level, we isolated and characterized the human U1-A gene. The human U1-A protein appears to be encoded by a single-copy gene and its locus has been mapped to the q arm of chromosome 19. The gene, about 14-16 kb in length, consists of six exons. The regions homologous to the U2-B" gene are not limited to single exons and are mostly not confined by exon-exon junctions in the corresponding U1-A mRNA. However, the proline-rich region of U1-A, absent in U2-B", is encoded by a single exon, suggesting a specific function for this domain of U1-A. The region of the cap site and upstream sequences contain interesting similarities to the promoter region of other snRNP protein-encoding genes and several housekeeping genes, in particular the vertebrate ribosomal protein-encoding genes. Hybridization experiments with various vertebrate genomic DNAs revealed that U1-A sequences are evolutionarily conserved in all tested vertebrate genomes, except for chicken, duck and pigeon. The divergence of these avian genomes is probably typical for the class of birds.
Nelissen
R L
RL
Department of Biochemistry, University of Nijmegen, The Netherlands.
Sillekens
P T
PT
Beijer
R P
RP
Geurts van Kessel
A H
AH
van Venrooij
W J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D005075:Biological Evolution; D002888:Chromosomes, Human, Pair 19; D004247:DNA; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012261:Ribonucleoproteins / Q000235:genetics* / Q000302:isolation & purification; D017411:Ribonucleoproteins, Small Nuclear; D012689:Sequence Homology, Nucleic Acid
D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D004247:DNA