How do I script a GUI Texture as a button, if it's being called from a public variable? [C#]

I have a simple UI Set up, that uses a few GUI Texture on Screen, to act as the player controls. I want to simply say, “When this GUITexture is Pressed, Do this”. Here’s my problem. To make it way easier on me, I’m using Public variables in a “Master Script”. So I can simply drag an drop all of my textures into the inspector, and everything is set up for me. How can I call OnMouseDown (Or something similar) on these GUITexture variables? Thanks!

This is my example of how I would do it

Script per GUITexture:

public class GUITextureClick : MonoBehaviour
{

    MasterScript masterScript;

    void Start()
    {

        //Obviously has to be changed to fit your setup
        masterScript = GameObject.Find("/MyMasterScriptObject").GetComponent<MasterScript>();

    }

    void OnMouseDown()
    {

        MasterScript.OnMouseDown(this.gameObject);

    }

}

Your master script would implement this function:

public void OnMouseDown(GameObject sender)
{

    switch(sender.transform.name)//One way to check which texture got clicked
    {
    
    case "Button1":

        break;

    }

}

All you would have to do now is assign the GUITextureClick component to all textures, if you think THAT would be a hassle then that’s also quite simple, just select all of them and assign the component through the component menu: Component->Scripts->GUITextureClick once it’s added to your project.