| Abstract
| - Parotld protein (parotin) was isolated from bovine parotid glands. To analyze the active site of parotid protein, the parotid subunit (PS) was digested by trypsin and then fractionated on a Sephadex G-25 column. Fraction A induced mainly polyclonal antibody responses and interleukin 1 (IL-1)-like activities. FrAA-1, consisting of 58 amino acids (LYILYFFQSDNEDKEKVVRQEEGEE-RITALLMNGSALKQEEWWEGKEDTDDTAIVLLK) was isolated from fraction A bychromatography on QAE-Sephadex A-25 columns. FrAA -1 was found to possess IL-1-like activity. There was only 29% homology between FrAA-1 and four IL-1-molecules. When 10- and 20-residue peptides based on the amino acid sequence of FrAA-1 were synthesized, P-10.2 (TDDTAIVLLK) alone exerted an IL-1-like effect on C3H/HeJ thymocytes, whereas P-20, 1 (SDNEDKEKWRQEEGEERIT) alone elicited polycional IgM and IgG antibody production in human lymphocytes. These results suggest that the active sites for polyclonal B-cell activator (PBA) and IL-1-like activity have different locations in FrAA-1.
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