Conversion of domains into subunits in the processing of egg yolk biotin-binding protein I.
Biotin-binding protein I (BBP-I), a protein that differs in its heat stability at low concentrations from that of BBP-II, has been purified from the yolk of hen oocytes and compared to BBP-II. Rabbit antiserum to BBP-II cross-reacts with identity to BBP-I. The molecular mass of BBP-I under denaturing conditions is about 68 kDa, a value four times that of BBP-II. Limited trypsin proteolysis of BBP-I generates subunits of 18 kDa with intermediate forms of approximately 51 and 34 kDa. The NH2-terminal sequence of BBP-I is very similar to that of BBP-II but has little of the polymorphism that is presumed to be generated at several positions by the slightly different subunits of BBP-II. These results indicate an unusual processing pathway in which four tandemly repeated biotin-binding domains of BBP-I become the subunits of BBP-II after limited proteolysis.
Bush
L
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Department of Chemistry and Biochemistry, University of Delaware, Newark 19716.
White
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HB
D000595:Amino Acid Sequence; D000818:Animals; D001360:Avidin / Q000235:genetics; D001710:Biotin / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics* / Q000302:isolation & purification; D002645:Chickens; D004530:Egg Yolk; D005260:Female; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D011110:Polymorphism, Genetic; D011487:Protein Conformation
D002352:Carrier Proteins; D046911:Macromolecular Substances; D010446:Peptide Fragments; C017071:biotin-binding proteins; D001360:Avidin; D001710:Biotin