A partial syndecan-2 sequence (147bp) was obtained from chicken embryonic fibroblast poly(A)+ RNA by reverse transcription–PCR. This partial sequence was used to produce a 5′-end-labelled probe. A chicken liver cDNA library was screened with this probe, and overlapping clones were obtained encompassing the entire cDNA of 3kb. The open reading frame encodes a protein of 201 amino acids. The cytoplasmic domain is identical with that of mammalian syndecan-2, and highly similar to those of Xenopus laevis and zebrafish syndecan-2. The transmembrane domain is identical with that of mammalian and zebrafish syndecan-2, and highly similar to that of Xenopus laevis syndecan-2. The ectodomain is 45–62% identical with that of zebrafish, Xenopus laevis and mammalian syndecan-2. Two coding single nucleotide polymorphisms were observed. In vitro transcription and translation yielded a product of 30kDa. Western blotting of chicken embryonic fibroblast cell lysates with species-specific monoclonal antibody mAb 8.1 showed that chicken syndecan-2 is substituted with heparan sulphate, and that the major form of chicken syndecan-2 isolated from chicken fibroblasts is consistent with the formation of SDS-resistant dimers, which is common for syndecans. A 5′-end-labelled probe hybridized to two mRNA species in chicken embryonic fibroblasts, while Northern analysis with poly(A)+ RNAs from different tissues of chicken embryos showed wide and distinct distributions of chicken syndecan-2 during embryonic development. This pattern was different from that reported for syndecan-4, but consistent with the roles of syndecan-2 in neural maturation and in mesenchymal–matrix interactions.
Abbreviations used: C1 and C2 regions, conserved regions 1 and 2; cSNP, coding single nucleotide polymorphism; GAG, glycosaminoglycan; GST, glutathione S-transferase; RT-PCR, reverse transcription–PCR; V region, variable region.
Present address: Division of Biomedical Sciences, Imperial College of Science, Technology and Medicine, London SW7 2AZ, U.K.
The nucleotide sequence data reported in this paper have been submitted to the GenBank™/EMBL/DDBJ/GSDB databases under accession numbers AF508228 and AF508229.