Identical and similar amino acid sequences in the pulmonary surfactant proteins SP-B and SP-C and hemerythrin and myohemerythrin--an example of "biochemical Velcro"?

A remarkable sequence similarity has been found in the N-terminal regions of hemerythrin, myohemerythrin and the pulmonary surfactant protein, SP-B. There is a very high degree of similarity in the first 9-10 amino acids in the sequences of these proteins. A less striking but significant sequence similarity has been found between a region of five amino acids in the N-terminal portion of pulmonary surfactant protein SP-C and the C-terminal portion of hemerythrin and myohemerythrin. Functional similarities are not obvious for these sets of proteins. We hypothesize that the similar sequences may be involved in the association of peptide regions with one another.