CHARACTERIZATION AND EXPRESSION OF IRON REGULATORY PROTEIN-2 (IRP2) -PRESENCE OF MULTIPLE IRP2, TRANSCRIPTS REGULATED BY INTRACELLULAR IRON LEVELS

Citation
B. Guo et al., CHARACTERIZATION AND EXPRESSION OF IRON REGULATORY PROTEIN-2 (IRP2) -PRESENCE OF MULTIPLE IRP2, TRANSCRIPTS REGULATED BY INTRACELLULAR IRON LEVELS, The Journal of biological chemistry, 270(28), 1995, pp. 16529-16535
Citations number
43
Categorie Soggetti
Biology
ISSN journal
00219258
Volume
270
Issue
28
Year of publication
1995
Pages
16529 - 16535
Database
ISI
SICI code
0021-9258(1995)270:28<16529:CAEOIR>2.0.ZU;2-V
Abstract
Iron regulatory proteins (IRP1 and IRP2) are RNA-binding proteins that bind to stem-loop structures, termed iron-responsive elements (IREs), present in either the 5'- or 3'-untranslated regions of specific mRNA s. The binding of IRPs to 5'-IREs inhibits translation of mRNA, wherea s the binding of IRPs to 3'-IREs stabilizes mRNA. To study the structu re and regulation of IRP2, we isolated cDNAs for rat and human IRP2. T he derived amino acid sequence of rat IPR2 is 93% identical with that of human IRP2 and is present in lower eukaryotes, indicating that IRP2 is highly conserved, IRP1 and IRP2 share 61% overall amino acid ident ity, IRP2 is ubiquitously expressed in rat tissues, the highest amount s present in skeletal muscle and heart, IRP2 is encoded by multiple mR NAs of 6.4, 4.0, and 3.7 kilobases, The 3'-untranslated region of rat IRP2 contains multiple polyadenylation signals, two of which could acc ount for the 4.0 kb and 3.7-kb mRNAs, The 3.7-kb mRNA is increased in iron-depleted cells and occurs with a reciprocal decrease in the 6.4-k b transcript, These data suggest that the 3.7-kb mRNA is produced by a lternative poly(A) site utilization in iron-depleted cells.