ARACHIDONIC-ACID BINDS TO APOLIPOPROTEIN-D - IMPLICATIONS FOR THE PROTEINS FUNCTION

The lipocalin apolipoprotein D (ApoD) is associated in human plasma wi th lecithin-cholesterol acyl transferase. It has also been found in hi gh concentration in the fluid of gross cystic disease of the mammary g land, Using protein fluorescence quenching, it is shown that ApoD bind s arachidonic acid (K-a of 1.6 x 10(8) M(-1)) and as previously known progesterone (K-a of 2.5 x 10(6) M(-1)), but neither cholesterol nor a ny of the other prostanoid molecules examined had measurable affinity, This specific binding of arachidonate, also observable directly, sugg ests a role for ApoD in the mobilisation of arachidonic acid, and henc e prostaglandin synthesis.