title: SS-B (La) nuclear antigen. Organization in structural domains of the protein moiety.
abstract: Stable degradation products, obtained by digestion with endogenous and V8 proteases of calf thymus SS-B (La) antigenic protein, have been studied. The most characteristic fragments have molecular masses of 47, 30, 23 and 17 kDa. The 47-kDa and 30-kDa fragments are complex and are constituted of a number of species of different isoelectric points, as has been described for the SS-B protein molecule from other sources. Degradation products from the entire SS-B nuclear antigen still contain the 30-kDa SS-B fragment, suggesting that the 30-kDa region of the SS-B protein molecule is firmly attached to the RNA moiety. A model is presented that implies the presence of two hinge regions sensitive to proteases and three structural domains that correspond to segments of 30 kDa, 17 kDa and 5-6 kDa.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism; D006680:HLA Antigens / Q000302:isolation & purification; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D013950:Thymus Gland / Q000378:metabolism; D014157:Transcription Factors / Q000302:isolation & purification
chemical_list: D006680:HLA Antigens; D010446:Peptide Fragments; D014157:Transcription Factors