autopostback of textchange inside gridview

I have textboxes within a gridview that need to post back with changes for recalculation. What handles the post back? The gridview rowcommand? How do I setup the triggers?

Below is a sample of my code.

<asp:UpdatePanel ID="UpdatePanel1" runat="server"><ContentTemplate><asp:GridView ID="materialGridView" runat="server"
                    AutoGenerateColumns="false" ><Columns><asp:BoundField DataField="MaterialTypeName" HeaderText="Material Type" /><asp:TemplateField><HeaderTemplate>
                                Quantity</HeaderTemplate><ItemTemplate><asp:TextBox ID="quantityTextBox" runat="server" Width ="50"
                                             OnTextChanged="recalculateMaterialCost" AutoPostBack="true"></asp:TextBox></ItemTemplate></asp:TemplateField><asp:TemplateField><HeaderTemplate>
                                Material</HeaderTemplate><ItemTemplate><asp:DropDownList ID="materialDropDownList" runat="server" Width="200"></asp:DropDownList></ItemTemplate></asp:TemplateField><asp:TemplateField><HeaderTemplate>
                                Color</HeaderTemplate><ItemTemplate><asp:TextBox ID="colorTextBox" runat="server" Width="100" Enabled="false" ></asp:TextBox></ItemTemplate></asp:TemplateField><asp:TemplateField><HeaderTemplate>
                                RBK</HeaderTemplate><ItemTemplate><asp:RadioButton id="rbkRadioButton" runat="server" AutoPostBack="true" /><asp:TextBox ID="rbkPriceTextBox" runat="server" Width="50"
                                             OnTextChanged="recalculateMaterialCost" AutoPostBack="true"></asp:TextBox></ItemTemplate></asp:TemplateField><asp:TemplateField><HeaderTemplate>
                                Wimsatt</HeaderTemplate><ItemTemplate><asp:TextBox ID="wimsattPriceTextBox" runat="server" Width="50"
                                             OnTextChanged="recalculateMaterialCost" AutoPostBack="true"></asp:TextBox><asp:RadioButton id="wimsattRadioButton" runat="server" AutoPostBack="true" /></ItemTemplate></asp:TemplateField></Columns></asp:GridView></ContentTemplate><Triggers><asp:AsyncPostBackTrigger ControlID ="quantityTextBox" EventName ="TextChanged" /><asp:AsyncPostBackTrigger ControlID ="rbkPriceTextBox" EventName ="TextChanged" /><asp:AsyncPostBackTrigger ControlID ="wimsattPriceTextBox" EventName ="TextChanged" /><asp:AsyncPostBackTrigger ControlID ="rbkRadioButton" EventName ="CheckedChanged" /><asp:AsyncPostBackTrigger ControlID ="wimsattRadioButton" EventName ="CheckedChanged" /></Triggers></asp:UpdatePanel>