Expression of a Xenopus counterpart of mammalian syndecan 2 during embryogenesis.
We have identified a Xenopus cDNA, XS-2, by screening a Xenopus embryonic stage-22-24 cDNA library with a DNA probe encoding the transmembrane and cytoplasmic domains of mouse syndecan 1. The 1.4 kb cDNA consists of an open reading frame of 642 nucleotides encoding a protein of 191 amino acids. The predicted protein of 20869 Da contains a 25-amino acid putative transmembrane domain and a 32-amino acid putative cytoplasmic domain, both of which are highly similar to the corresponding regions of rat syndecan 2 (92% identity) and to a lesser degree those of rat syndecans 1, 3 and 4 (62, 64 and 78% respectively). The putative N-terminal ectodomain contains a possible attachment site for heparan sulphate, identical with the comparable glycosaminoglycan-attachment sequence of rat syndecan 2. Polyclonal antisera raised against recombinant ectodomain of XS-2, expressed as a fusion protein, recognized a heparan sulphate proteoglycan in XTC cell-culture medium. This proteoglycan bound to DEAE-Sephacel and was eluted with 1 M NaCl; digestion with heparitinase but not chondroitinase ABC resulted in the identification of a 46 kDa protein by these antisera. Northern-blot analysis indicated that XS-2 identifies two Xenopus mRNA species approx. 4 and 2 kb in size in embryos ranging in maturation from the 64-cell stage to stage 54. These results demonstrate that a heparan sulphate proteoglycan, similar to syndecan 2, is expressed during Xenopus embryogenesis.
Rosenblum
N D
ND
Division of Nephrology, Hospital for Sick Children, University of Toronto, Ont., Canada.
Botelho
B B
BB
Bernfield
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D018507:Gene Expression Regulation, Developmental; D006497:Heparan Sulfate / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D011509:Proteoglycans / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D053669:Syndecan-2; D014981:Xenopus / Q000196:embryology* / Q000235:genetics; D029867:Xenopus Proteins
D018076:DNA, Complementary; D006497:Heparan Sulfate; D008562:Membrane Glycoproteins; D011509:Proteoglycans; D012333:RNA, Messenger; D053669:Syndecan-2; D029867:Xenopus Proteins; C508246:Sdc2 protein, mouse; C508247:Sdc2 protein, rat; C508248:sdc2 protein, Xenopus