Protein Hal is a human gamma4 heavy-chain disease protein whose molecular weight is reduced from 55,000 to 25,000 in 6 M guanidine due to the lack of disulfide bonds between heavy chains. Studies of aminoacid sequence indicate that it contains a gap of about 240 residues, starting 10 residues from the N-terminal end and including the rest of the Fd fragment, as well as the hinge region. Normal sequence apparently resumes at a methionine residue (position 252) in the second constant domain (C(H)2) and seems normal from there to the carboxyl end of the molecule. These results imply that reinitiation of translation at an internal AUG codon occurs in protein Hal.
Amino Acid Sequence Carbon Isotopes