Tissue-specific processing of the Surf-5 and Surf-4 mRNAs.
The mouse surfeit locus is an unusually tight cluster of at least six "housekeeping" genes that do not share any sequence homology and whose gene organization may play a role in gene expression. The transcription of each of the five well-characterized genes (Surf-1 to -5) alternates with respect to its neighbor(s) and no more than 159 bp separates any two adjacent genes with the Surf-4 and Surf-2 genes overlapping at their 3' ends by 133 bp. In this work, the expression of the Surf-5 and Surf-4 genes has been examined in various mouse tissues. In addition to the ubiquitously expressed 3.5-kb Surf-5 mRNA, a second alternatively spliced Surf-5 mRNA, Surf-5b, was discovered that was highly expressed in the brain, heart, testis, and skeletal muscle. The alternative splice donor site of the Surf-5b mRNA is similar to splice donor sites found in neuron-specific mRNAs. Surf-5b encodes a unique protein, which, like the ubiquitous Surf-5 protein, has been found to be primarily located in the soluble fraction of the cytoplasm. The expression of the Surf-5b protein was also found to increase in embryonal carcinoma cells differentiated into neuronal cultures. Although the Surf-5 gene is highly conserved through evolution, the presence of the Surf-5b alternative splice may be restricted to higher vertebrates. The Surf-4 gene was ubiquitously expressed in eight different mouse tissues; however, the ratios of the three previously reported Surf-4 mRNAs (two of which are known to derive from different sites of polyadenylation) altered dramatically between tissues. The use of different forms of mRNA processing for regulation of tissue-specific expression of ubiquitously expressed genes is discussed.
Garson
K
K
Eukaryotic Gene Organization and Expression Laboratory, Imperial Cancer Research Fund, Lincoln's Inn Fields, London, UK.
Duhig
T
T
Fried
M
M
D016475:3T3 Cells; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D015870:Gene Expression; D006801:Humans; D056892:Mediator Complex; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*; D014018:Tissue Distribution; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; C484358:MED22 protein, human; D056892:Mediator Complex; D008565:Membrane Proteins; D011506:Proteins; D012333:RNA, Messenger; C094364:SURF4 protein, human; C098231:Surf5 protein, mouse; D014157:Transcription Factors