About the Lectin

Two new mannose-binding lectins were isolated from
garlic (Allium sativum, ASA) and ramsons (Allium ursinum,
AUA) bulbs, of the family Alliaceae. ASA reacted strongly with
a synthetic linear (1—-3)-alpha-D-mannan and S. cerevisiae
mannan, weakly with a synthetic (1—-6)-alpha-D-mannan, and
failed to precipitate with galactomannans from T. gropengiesseri
and T. lactis-condensi, a linear mannopentaose, and murine IgM.
On the other hand, AUA gave a strong reaction of precipitation
with murine IgM, and good reactions with S. cerevisiae mannan
and both synthetic linear mannans, suggesting that the two
lectins have somewhat different binding specificities for alpha-
D-mannosyl units. These two lectins exhibit different binding
specificity for alpha-D-mannosyl units.¹

Lectin cDNA clones for two different lectins from
garlic (Allium sativum L.) bulbs, ASAI and ASAII (ASA,
Allium sativum agglutinin), were isolated and characterized.
The first lectin, ASAI, is a heterodimer composed of two
different subunits of 11.5 kDa and 12.5 kDa. It is translated
from an mRNA of 1400 nucleotides encoding a polypeptide
of 306 amino acids with two very similar domains. N-terminal
sequencing of the two polypeptides of the mature lectin
confirmed that both subunits are derived from the same
precursor and that each corresponds to one of the two domains
in the sequence. In contrast to ASAI, the second garlic lectin,
ASAII, is a homodimer of two identical 12-kDa subunits. It is
translated from an mRNA of approximately 800 nucleotides
encoding a polypeptide of 154 amino acids. Interestingly, the
coding region of the ASAII cDNA clones is almost identical to
that of the second domain of the ASAI cDNA clones.²

REFERENCES

1. Kaku H, et al. Carbohydr Res. 1992 May 22;229(2):347-53.
2. van Damme EJ,et al. Eur J Biochem. 1992 Jun 1;206(2):413-20.