THE AMINO-ACID-SEQUENCE OF A BOAR TRANSITION PROTEIN-3

The boar transition protein 3 (TP3) was extracted with acid from the i solated late spermatid nuclei or directly from the testes, fractionate d with trichloroacetic acid, and reduced and carboxymethylated (RCM-). RCM-TP3 from the nuclei was purified by HPLCs on Nucleosil 300 7Cl8 a nd Hitachi #3057, and that from the testes, by ion-exchange chromatogr aphy on CM-Sephadex C-25 and HPLCs on Nucleosil 300 7Cl8 and Chemcosor b 7C8. The two TP3 preparations were identical in acid-urea- and SDS-g el electrophoretic mobilities and amino acid composition. The primary structure of TP3 was determined by manual Edman degradation of the pep tides obtained by lysyl endopeptidase-digestion or by alpha-chymotryps in-digestion of RCM-TP3 from the testes, and by automated Edman degrad ation of it. Boar TP3 is a basic protein of 76 residues: GKVRKIYKKVKRP LHVCSRKKYSPKVITTSRRQKRARRANKFETIP-OH, and it shows 27% homology with b oar TP1. TP3 is composed of an N-terminal region (1-19) having two cha racteristic tryptophan residues (8 and 18) which is absent in the know n TP1 group, and a C-terminal region (20-76) having a close resemblanc e to boar TP1.