Structure of the murine Mac-2 gene. Splice variants encode proteins lacking functional signal peptides

• Published in: The Journal of biological chemistry Vol. 268; no. 17; pp. 12393 - 12400
• Main Authors: ROSENBERG, I. M, IYER, R, CHERAYIL, B, CHIODINO, C, PILLAI, S
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15-06-1993
• Subjects: Alternative Splicing; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Animals; Antigens, Differentiation - analysis; Antigens, Differentiation - genetics; Base Sequence; Biological and medical sciences; Cell Line; Cloning, Molecular; DNA; DNA Probes; Exons; Fundamental and applied biological sciences. Psychology; Galectin 3; Galectin 4; Genomic Library; Glycoproteins; Hemagglutinins - analysis; Hemagglutinins - genetics; Introns; Lectins - genetics; Mice - genetics; Molecular Sequence Data; Oligodeoxyribonucleotides; Protein Sorting Signals - genetics; Proteins; Restriction Mapping; Subcellular Fractions - chemistry; Lectin; Alternative splicing; Vertebrata; Mammalia; Gene; Mouse; Rodentia; Gene organization; Primary structure; Glycoproteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(18)31403-0

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.