Journal of Lipid Research, Vol 26, 241-247, Copyright © 1985 by Lipid Research, Inc.
Lipophorin of the larval honeybee, Apis mellifera L
SL Robbs, RO Ryan, JO Schmidt, PS Keim and JH Law
Most insects have a major lipoprotein species in the blood (hemolymph) that
serves to transport fat from the midgut to the storage depots in fat body
cells and from the fat body to peripheral tissues. The generic name
lipophorin is used for this lipoprotein. In larvae of the honeybee, Apis
mellifera, a lipophorin has been found with properties that correlate well
with those of the only other lipophorin reported for an immature insect,
that of the tobacco hornworm, Manduca sexta. The honeybee lipophorin (Mr =
530,000) has a density of 1.13 g/ml, contains approximately 41% lipid and
59% protein, and contains two apoproteins, apoLp-I, Mr = 250,000 and
apoLp-II, Mr = 80,000, both of which are glycosylated. The lipids consist
predominantly of polar lipids, of which phospholipids and diacylglycerols
represent 60% of the total. When the intact lipophorin is treated with
trypsin, apoLp-I is rapidly proteolyzed, while apoLp-II is resistant,
indicating a difference in exposure of the two apoproteins to the aqueous
environment. Honeybee apoLp-II cross-reacts with antibodies to M. sexta
apoLp-II, but not to anti-M. sexta apoLp-I. No cross-reactivity of honeybee
apoLp-I to anti-M. sexta apoLp-I was observed.