Title : The complete amino acid
sequence of human
complement factor H
Abstract :
- The complete amino acid sequence of the human complement system regulatory protein , factor H, has been derived from sequencing three overlapping cDNA clones
- The sequence consists of 1213 amino acids arranged in 20 homologous units, each about 60 amino acids long, and an 18-residue leader sequence
- The 60-amino-acid-long repetitive units are homologous with those found in a large number of other complement and non-complement proteins
- Two basic C-terminal residues , deduced from the cDNA sequence , are absent from factor H isolated from outdated plasma
- A tyrosine/histidine polymorphism was observed within the seventh homologous repeat unit of factor H
- This is likely to represent a difference between the two major allelic variants of factor H
- The nature of the cDNA clones indicates that there is likely to be an alternative splicing mechanism, resulting in the formation of at least two species of factor H mRNA