Shared protein components of SINE RNPs.
The heterogeneous, short RNAs produced from the high, copy, short mobile elements (SINEs) interact with proteins to form RNA-protein (RNP) complexes. In particular, the BC1 RNA, which is transcribed to high levels specifically in brain and testis from one locus of the ID SINE family, exists as a discrete RNP complex. We expressed a series of altered BC1, and other SINE-related RNAs, in several cell lines and tested for the mobility of the resulting RNP complexes in a native PAGE assay to determine which portions of these SINE RNAs contribute to protein binding. When different SINE RNAs were substituted for the BC1 ID sequence, the resulting RNPs exhibited the same mobility as BC1. This indicates that the protein(s) binding to the ID portion of BC1 is not sequence specific and may be more dependent upon the secondary structure of the RNA. It also suggests that all SINE RNAs may bind a similar set of cellular proteins. Deletion of the A-rich region of BC1 RNA has a marked effect on the mobility of the RNP. Rodent cell lines exhibit a slightly different mobility for this shifted complex when compared to human cell lines, reflecting evolutionary differences in one or more of the protein components. On the basis of mobility change observed in RNP complexes when the A-rich region is removed, we decided to examine poly(A) binding protein (PABP) as a candidate member of the RNP. An antibody against the C terminus of PABP is able to immunoprecipitate BC1 RNA, confirming PABP's presence in the BC1 RNP. Given the ubiquitous role of poly(A) regions in the retrotransposition process, these data suggest that PABP may contribute to the SINE retrotransposition process.
West
Neva
N
Tulane Cancer Center, SL-66, Department of Environmental Health Sciences, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
Roy-Engel
Astrid M
AM
Imataka
Hiroaki
H
Sonenberg
Nahum
N
Deininger
Prescott
P
D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D006801:Humans; D066298:In Vitro Techniques; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics*; D020086:Short Interspersed Nucleotide Elements; D013045:Species Specificity
D017931:DNA Primers; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins