Galectin-8. A new rat lectin, related to galectin-4.
A protein of 35 kDa which has the characteristic properties of galectins (S-type lectins) was cloned from rat liver cDNA expression library. Since names for galectins 1-7 were already assigned, this new protein was named galectin-8. Three lines of evidence demonstrate that galectin-8 is indeed a novel galectin: (i) its deduced amino acid sequence contains two domains with conserved motifs that are implicated in the carbohydrate binding of galectins, (ii) in vitro translation products of galectin-8 cDNA or bacterially expressed recombinant galectin-8 are biologically active and possess sugar binding and hemagglutination activity, and (iii) a protein of the expected size (34 kDa) that binds to lactosyl-Sepharose and reacts with galectin-8-specific antibodies is present in rat liver and comprises approximately 0.025% of the total Triton X-100-soluble hepatic proteins. Overall, galectin-8 is structurally related (34% identity) to galectin-4, a soluble rat galectin with two carbohydrate-binding domains in the same polypeptide chain, joined by a link peptide. Nonetheless, several important features distinguish these two galectins: (i) Northern blot analysis revealed that, unlike galectin-4 that is confined to the intestine and stomach, galectin-8 is expressed in liver, kidney, cardiac muscle, lung, and brain; (ii) unlike galectin-4, but similar to galectins-1 and -2, galectin-8 contains 4 Cys residues; (iii) the link peptide of galectin-8 is unique and bears no similarity to any known protein; (iv) the N-terminal carbohydrate-binding region of galectin-8 contains a unique WG-E-I motif instead of the consensus WG-E-R/K motif implicated as playing an essential role in sugar-binding of all galectins. Together with galectin-4, galectin-8 therefore represents a subfamily of galectins consisting of a tandem repeat of structurally different carbohydrate recognition domains within a single polypeptide chain.
Hadari
Y R
YR
Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel.
Paz
K
K
Dekel
R
R
Mestrovic
T
T
Accili
D
D
Zick
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D005333:Fetus; D037541:Galectin 4; D037161:Galectins; D015870:Gene Expression; D015723:Gene Library; D006388:Hemagglutinins / Q000096:biosynthesis* / Q000737:chemistry; D037102:Lectins / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D000906:Antibodies; D017931:DNA Primers; D037541:Galectin 4; D037161:Galectins; D006388:Hemagglutinins; C091991:LGALS8 protein, human; D037102:Lectins; D010455:Peptides; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins