Role of basic residues of human lactoferrin in the interaction with B lymphocytes.
We have previously demonstrated that lactoferrin was incorporated into B lymphocytes and that a trypsin treatment for a short period reduced the number of lactoferrin molecules incorporated into B lymphocytes. An N-terminal sequence analysis revealed that the mild trypsin treatment had cleaved the three N-terminal amino acids, Gly1-Arg2-Arg3. Chemical conjugation of lost sequence analogue Gly-Arg-Arg-Gly with the mildly digested lactoferrin recovered the interaction with B lymphocytes, while conjugation of acetyl-Arg-Arg-Gly, a deamino analogue of Gly-Arg-Arg-Gly, did not recover the interaction. This shows that the N-terminal basic region containing N-terminal Gly played an important role in the interaction with B lymphocytes. Acylation of the amino groups of lactoferrin also significantly reduced the interaction with B lymphocytes, and an O-methylisourea treatment of the amino groups, which preserved the positive charge, hardly affected the interaction. These results suggest that both the N-terminal basic region and the basic characteristics of the whole molecule contributed to its interaction with B lymphocytes.
Kawasaki
Y
Y
Technical Research Institute, Snow Brand Milk Products Co. Ltd., Kawagoe, Japan.
Sato
K
K
Shinmoto
H
H
Dosako
S
S
D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007781:Lactoferrin / Q000737:chemistry / Q000378:metabolism*
D007781:Lactoferrin