Calling FilterExpression

[Appu]

Hi i have inbuilt filterexpression like below:
<telerik:GridBoundColumn SortExpression="OrgName1" HeaderStyle-Width="5.33%" ItemStyle-Wrap="true"
                            UniqueName="OrgName1" CurrentFilterFunction="contains" AutoPostBackOnFilter="true"
                            FooterText="OrgName :" Aggregate="CountDistinct" HeaderText="OrgName"  ShowFilterIcon="false"
                            DataField="OrgName1">

I would like to call this controls filterexpression value in codebehind whenever i switched over from this input control to  another control

Because i am getting filter combo value in selectechanged event from serverside so that i can get combo value during that event fired.
But the above code how can i cal event and get the value of that input control from server side

Appu