The N-terminal 209-aa domain of high molecular- weight 4.1R isoforms abrogates 4.1R targeting to the nucleus
AUTOR(ES)
Luque, Carlos M.
FONTE
The National Academy of Sciences
RESUMO
An extensive repertoire of protein 4.1R isoforms is predominantly generated by alternative pre-mRNA splicing and differential usage of two translation initiation sites. The usage of the most upstream ATG (ATG-1) generates isoforms containing N-terminal extensions of up to 209 aa compared with those translated from the downstream ATG (ATG-2). To characterize nonerythroid 4.1R proteins translated from ATG-1 and analyze their intracellular localization, we cloned 4.1R cDNAs containing this translation initiation site. Six different clones were isolated from the nucleated human MOLT-4 T-cell line by reverse transcriptase–PCR techniques. Transient expression of the six ATG-1-translated 4.1R isoforms tagged with a c-Myc epitope revealed that all of them predominantly distributed to the plasma membrane and the endoplasmic reticulum. Staining of MOLT-4 cell plasma membranes but not nuclei was also observed by immunofluorescence microscopy by using an antibody specific to the N-terminal extension. Consistent with this, the antibody reacted with a major endogenous protein of ≈145 kDa present in nonnuclear but absent from nuclear fractions prepared from MOLT-4 cells. Because these data suggested that ATG-1-translated 4.1R isoforms were predominantly excluded from the nucleus, we fused the 209-aa domain to nuclear 4.1R isoforms encoded from ATG-2 and observed that this domain inhibited their nuclear targeting. All these results indicate that the N-terminal domain of ATG-1-translated 4.1R isoforms plays a pivotal role in differential targeting of proteins 4.1R.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=24749Documentos Relacionados
- Targeting to Transcriptionally Active Loci by the Hydrophilic N-Terminal Domain of Drosophila DNA Topoisomerase I
- The RAG1 N-terminal domain is an E3 ubiquitin ligase
- Crystal structure of the Sec18p N-terminal domain
- Localization of Cell Division Protein FtsK to the Escherichia coli Septum and Identification of a Potential N-Terminal Targeting Domain
- DsbC activation by the N-terminal domain of DsbD