I have found the answer:

in the user control ascx:

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="TabControl.ascx.cs" Inherits="TabControl" %>

<table class="content" border="0" cellpadding="0" cellspacing="0">

<tr>

<td><div class="tab_header" ><ul><li><span style="font-weight: bold;" runat="server" id="divHead">&nbsp;</span></li></ul></div></td>

</tr>

<tr>

<td class="tabContent">

<table cellpadding="3" cellspacing="0" border="0" width="100%"><tr><td>

<asp:GridView ID="gvData" runat="server" DataSourceID="sqlData">

<PagerSettings Mode="NumericFirstLast" PageButtonCount="10" />

<EmptyDataTemplate>

<asp:Literal ID="litNoData" runat="server" Text="no records"></asp:Literal>

</EmptyDataTemplate>

</asp:GridView>

</td></tr></table>

<asp:SqlDataSource runat="server" ID="sqlData" ConnectionString="<%$ConnectionStrings:MyConnection %>" CancelSelectOnNullParameter="true" OnSelecting="sqlData_Selecting">

</asp:SqlDataSource>

</td>

</tr>

</table>

In the ascx.cs:

[ParseChildren(true)]
[PersistChildren(true)]
[ToolboxData("<{0}:TabControl runat=server></TabControl>")]
public partial class TabControl : System.Web.UI.UserControl, INamingContainer
{
    #region Properties
    public string HeaderText
    {
        get { return divHead.InnerText; }
        set { divHead.InnerText = value; }
    }
    public string SqlConnectionString
    {
        get { return sqlData.ConnectionString; }
        set { sqlData.ConnectionString = value; }
    }
    public string SqlSelectCommand
    {
        get { return sqlData.SelectCommand; }
        set { sqlData.SelectCommand = value; }
    }

    [PersistenceMode(PersistenceMode.InnerProperty)] 
    public SqlDataSource MySqlData
    {
        get { return sqlData; }
        set { sqlData = value; }
    }

    #endregion
    #region Events
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void sqlData_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
    {
    }
    #endregion

}

and I use it in the aspx page like this:

<uc:TabControl runat="server" HeaderText="TabControl test" SqlSelectCommand="spTest">
                                            <MySqlData ConnectionString="<%$ConnectionStrings:MyConnection %>">
                                                <SelectParameters>
                                                   <asp:Parameter Name="IsChecked" DefaultValue="0" />
                                                 </SelectParameters>
                                            </MySqlData>    
                                        </uc:TabControl>