HUMAN FREE SECRETORY COMPONENT IS COMPOSED OF THE FIRST 585 AMINO-ACID-RESIDUES OF THE POLYMERIC IMMUNOGLOBULIN RECEPTOR

The main objective of this work was to unequivocally determine the C-t erminal sequence of human milk free secretory component (SC). It was f ound to end at arginine-585, i.e. 33 amino acids downstream from the m ajor heterogeneous C-terminal residue previously identified for colost rum SC, In contrast, our data showed that the C-terminal end of SC was found to be homogeneous. Conflicting assignments, Asp/Gln, a missing Asn-211, Asp/Asn, Glu/Gln were corrected and found to agree with the c DNA sequence, An Ala/Val substitution at position 562 (domain VI) was identified. Its genetic significance is uncertain at present. (C) 1997 Federation of European Biochemical Societies.