Biology Reference
In-Depth Information
21
In order to maintain the reading frames in the V-gene and the J-minigene, so
that the resulting protein can be functional, the total number of nucleotides
of the segment coding for CDRH3 must be divisible by three. However, the
number of nucleotides of the N/P segments on both ends of the D-minigene
can vary. As a result, all three reading frames of any D-minigene can be
used, as long as there is no termination codon. Furthermore, since the
recombination signal sequences on both sides of the D-minigene to join D to
J and V to D are similar, D-minigenes can be inverted. Thus, the
complementary strands of D-minigenes can also be used to code for
CDRH3. In human and mouse, however, the complementary strands are
found less frequently in the heavy chains of antibodies. In short, one
nucleotide sequence of a D-minigene has the capacity of coding for six
different amino acid sequences (Fig. 1-12).
Figure 1-12
. One nucleotide sequence of a D-minigene can code for
six different amino acid sequences
