Dissolve yeast and 1 teaspoon sugar in warm milk in a large bowl, stirring well; let stand 5 minutes or until bubbly. Add remaining sugar, shortening, salt, and 1 1/2 cups flour; beat at low speed of electric mixer until smooth. Stir in enough remaining flour to make a soft dough.
Place dough in a greased bowl, turning to grease top. Cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk.
Punch dough down, and let rest 5 minutes. Divide dough into 16 portions. Roll each portion into a 10-inch rope on a lightly floured surface. Loosely coil ropes on a greased baking sheet. Cover and repeat rising procedure 1 hour or until doubled in bulk. Bake at 350° for 15 minutes or until lightly browned. Brush rolls with melted butter, if desired.