Structure of the murine Mac-2 gene. Splice variants encode proteins lacking functional signal peptides.
The murine Mac-2 gene is composed of six exons dispersed over 10.5 kilobases. S1 nuclease mapping showed multiple transcription initiation sites, clustered within a 30-base pair region. Sequence analysis revealed that a consensus initiator sequence is located in this area which lacks a TATA motif. The untranslated first exon contains an alternative splice donor site, confirming the existence of two cDNA species with the potential to encode proteins differing at their NH2 termini. In vitro expression and translocation experiments demonstrate that both of the alternatively spliced variants of Mac-2 encode proteins which lack a functional signal peptide. Subcellular fractionation studies indicate that most of the Mac-2 protein is present in the cytosol. These results support the view that Mac-2 is exported from the cell by an unusual mechanism which does not depend on the presence of a signal peptide.
Molecular Immunology Laboratory, Cancer Center of the Massachusetts General Hospital, Boston.
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Rosenberg
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Iyer
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Cherayil
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Chiodino
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Pillai
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000943:Antigens, Differentiation / Q000032:analysis / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA; D015342:DNA Probes; D005091:Exons; D037502:Galectin 3; D037541:Galectin 4; D015698:Genomic Library; D006388:Hemagglutinins / Q000032:analysis / Q000235:genetics*; D007438:Introns; D037102:Lectins / Q000235:genetics; D051379:Mice / Q000235:genetics*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals / Q000235:genetics*; D015183:Restriction Mapping; D013347:Subcellular Fractions / Q000737:chemistry
D000943:Antigens, Differentiation; D015342:DNA Probes; D037502:Galectin 3; D037541:Galectin 4; D006388:Hemagglutinins; D037102:Lectins; D009838:Oligodeoxyribonucleotides; D021382:Protein Sorting Signals; D004247:DNA