Several protein families of different nature were studied for genetic relat
ionship, correct alignment; at non-homologous fragments, optimal sequence c
onsensus construction, and confirmation of their actual relevance. A compar
ison of the genetic semihomology approach with statistical approaches indic
ates a high accuracy and cognition significance of the former. This is part
icularly pronounced in the study of related proteins that show a low degree
of homology. The sequence multiple alignments were verified and corrected
with respect to the questionable, non-homologous fragments. The verified al
ignments were the basis for consensus sequence formation. The frequency of
six-codon amino acids occurrence versus position variability was studied an
d their possible role in amino acid mutational exchange at variable positio
ns is discussed.