COMPARISON OF THE AMINO-ACID-SEQUENCES OF TISSUE-SPECIFIC PARVALBUMINS FROM CHICKEN MUSCLE AND THYMUS AND POSSIBLE EVOLUTIONARY SIGNIFICANCE

Chicken leg muscle parvalbumin was digested with cyanogen bromide or trypsin or trypsin after citraconylation. Peptides isolated by reverse phase HPLC at pH 7.0 were subjected to acid hydrolysis and amino acid analysis and, in some cases, sequencing. The chicken muscle parvalbumin amino acid sequence has ca. 80% sequence identity with a-type parvalbumins from mammalian (rabbit, human and rat) muscle. By contrast, the chicken thymus parvalbumin ("avian thymic hormone") sequence is very similar to reptile (turtle, salamander and frog) muscle β-type parvalbumins. We hypothesize that the evolutionary appearance of the warm-blooded reptiles was accompanied by recruitment of the β parvalbumin isozyme for promotion of lymphocyte maturation. © 1991 Academic Press, Inc.