Isolation, Characterization, and Molecular Modeling of a Rheumatoid Factor from a Hepatitis C Virus Infected Patient with Sjögren's Syndrome

Lee, Yu-Ching; Tsai, Keng-Chang; Leu, Sy-Jye; Wang, Tuan-Jen; Liu, Chia-Yu; Yang, Yi-Yuan

The nucleotide sequences of VH and VL region of Fc-binding clones were determined. When compared to potential germline, the light chain and heavy chains of RFL11 were determined and shown the highest homology to VL1-16 and VH6-1 ( Table 2) . Three nucleotide differences were identified in CDR3 region of the light chain gene. Two changes in nucleotide positions 277 and 279 (GAT to CAG) resulted in amino acid residue that changed from Aspartate (D) to Glutamine (Q). The third change in nucleotide 284 (AGC to AAC) led to amino acid residue that changed from Serine (S) to Asparagine (N) (Figure 5(a) ). Similarly, two nucleotide changes in 158 and 171 of CDR2 of the heavy chain of RFL11 mutated Tyrosine (Y) to Phenylalanine (F) and Lysine (K) to Asparagine (N), respectively. As compared to JH6b germline gene, four continual residues were somatically mutated making NYYY to TTDF in CDR3 region ( Figure 5(b) ).