Rheumatoid arthritis-related antigen 47kDa (RA-A47) is a product of colligin-2 and acts as a human HSP47

Takako Hattori, Kojiro Takahashi, Yasutaka Yutani, Takuo Fujisawa, Tohru Nakanishi, Masaharu Takigawa

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


We previously isolated RA-A47, which is recognized as an antigen of rheumatoid arthritis (RA), from a human chondrosarcoma-derived cell line (HCS-2/8). The N-terminal 21-amino-acid sequence of RA-A47 had 81% homology to the deduced amino acid sequence of the human heat-shock protein (HSP) 47 gene, the colligin gene, and 100% homology to that of the colligin-2 gene. Moreover, as is HSP47, RA-A47 was a heat-inducible collagen-binding protein. To further characterize RA-A47, we isolated ra-a47 cDNA from HCS-2/8 cells and human periodontal ligament fibroblast (HPLF) cells. The isolated ra-a47 cDNAs from both cells were almost the same as that of colligin-2. C504 and G505 in the cDNA sequences of both cells and C598 in the cDNA of HCS-2/8 were different from the corresponding bases of colligin-2 cDNA. These differences were also observed in genomic DNA. colligin cDNA was not isolated. To show that the isolated cDNA encodes RA-A47 protein, it was expressed in Cos-7 cells. The produced protein was 47kDa and was recognized both with RA sera and antirat HSP47 antibody, indicating that it is RA-A47 and has structural similarity to HSP47. These results taken together with our previous findings show that RA-A47 is the putative colligin-2 gene product and behaves as a human HSP47. Although colligin has been considered the human HSP47 gene, failure to detect the colligin gene and its mRNA suggests that colligin does not exist in human cells and that the HSP47 gene is identical with colligin-2, which encodes RA-A47.

Original languageEnglish
Pages (from-to)328-334
Number of pages7
JournalJournal of Bone and Mineral Metabolism
Issue number6
Publication statusPublished - 2000


  • Chondrocyte
  • Genomic sequencing
  • Heat-shock protein (HSP)
  • Human chondrosarcoma-derived cell line (HCS-2/8)
  • Human periodontal ligament fibroblast (HPLF)
  • cDNA sequencing

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Endocrinology


Dive into the research topics of 'Rheumatoid arthritis-related antigen 47kDa (RA-A47) is a product of colligin-2 and acts as a human HSP47'. Together they form a unique fingerprint.

Cite this