Purification and cDNA cloning of Xenopus liver galectins and their expression.
We have characterized galectin family proteins in adult tissues of Xenopus laevis and purified 14-kDa and 36-kDa proteins from the liver. The liver galectins showed comparable hemagglutination activities to those of mammalian galectins. Furthermore, we isolated five galectin cDNAs from a Xenopus liver library. These cDNAs revealed that X. laevis galectins (xgalectins) form a family consisting of at least proto and tandem repeat types based on their domain structures, like the mammalian galectin family. Two proto-type xgalectins, -Ia and -Ib, exhibited a high sequence identity (91%) with each other at the amino acid level and were most similar (49-50% identity) to human galectin-1. From their sequence similarity and ubiquitous tissue distributions, xgalectins-Ia and -Ib both seemed to be Xenopus homologues of mammalian galectin-1. Three tandem repeat-type xgalectins were newly identified. Two of them, xgalectins-IIa and -IIIa, seemed to be homologous to human galectins-4 and -9, respectively, judging from their high sequence similarities (42-50% identity). However, xgalectin-IVa seemed to be a novel type. Distributions of mRNAs of xgalectins were analyzed by northern hybridization. In addition to adult tissues, either of three tandem repeat-type xgalectins were expressed in whole embryos. Moreover, amino acid sequence analysis of liver proteins indicated that xgalectins-Ia, -IIa, and -IIIa are produced as abundant galectins in the adult liver.
Shoji
Hiroki
H
Department of Endocrinology, Kagawa Medical University, 1750-1 Miki-cho, Kita-gun 761-0793, Japan.
Nishi
Nozomu
N
Hirashima
Mitsuomi
M
Nakamura
Takanori
T
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism*; D005260:Female; D037161:Galectins; D015723:Gene Library; D006386:Hemagglutination Tests; D006388:Hemagglutinins / Q000096:biosynthesis / Q000235:genetics*; D008099:Liver / Q000378:metabolism*; D008297:Male; D008322:Mammals; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014357:Trypsin; D014982:Xenopus laevis
D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D037161:Galectins; D006388:Hemagglutinins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D014357:Trypsin