Identification of an internal gene to the human Galectin-3 gene with two different overlapping reading frames that do not encode Galectin-3.
We previously reported that alternative transcripts were initiated within the second intron of the human Galectin-3 gene (LGALS3). We now demonstrate that these transcripts arise from an internal gene embedded within LGALS3 and named galig (Galectin-3 internal gene). Tissue-specific expression of galig was assayed by screening of several human tissues. Contrary to LGALS3, galig appears to be tightly regulated and principally activated in leukocytes from peripheral blood. Cloning and characterization of galig transcripts revealed that they contain two out-of-frame overlapping open-reading frames (ORFs). Transfection of expression vectors encoding enhanced green fluorescent protein (EGFP) chimeras indicated that both ORFs could be translated in proteins unrelated to Galectin-3. The ORF1 polypeptide targets EGFP to cytosol and nucleus whereas ORF2 targets EGFP to mitochondria. These results revealed the exceptional genetic organization of the LGALS3 locus.
Guittaut
M
M
Centre de Biophysique Moléculaire (affiliated with the University of Orléans), CNRS UPR4301, Rue Charles Sadron, 45071 Orléans Cedex 02, France.
Charpentier
S
S
Normand
T
T
Dubois
M
M
Raimond
J
J
Legrand
A
A
D000595:Amino Acid Sequence; D000943:Antigens, Differentiation / Q000235:genetics*; D001483:Base Sequence; D001798:Blood Proteins / Q000235:genetics*; D002451:Cell Compartmentation; D002467:Cell Nucleus; D003600:Cytosol; D037502:Galectin 3; D037161:Galectins; D006801:Humans; D008928:Mitochondria; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D014176:Protein Biosynthesis; D014018:Tissue Distribution; D014158:Transcription, Genetic
D000943:Antigens, Differentiation; D001798:Blood Proteins; D037502:Galectin 3; D037161:Galectins; C428445:LGALS3 protein, human