Dissolve yeast in warm water in large bowl. Add sugar, salt, egg, shortening, 1/4 cup cornmeal and 1 cup of flour. Blend 1 to 2 minutes on low speed, scraping bowl constantly. Beat 2 minutes on medium speed, scraping bowl occasionally. Stir in enough remaining flour to make dough easy to handle. Turn dough onto lightly floured surface; knead until smooth and elastic, about 5 minutes. Place in greased bowl; turn greased side up. Cover; let rise in warm place until double, 1 to 1 1/2 hours). Punch down dough. Flatten dough with hands or rolling pin into 18 x 9-inch rectangle. Fold crosswise into thirds, overlapping the two sides. Roll dough down tightly toward you, beginning at one of the open ends. Press with thumbs to seal. Pinch edges firmly to seal and fold ends under. Place in greased loaf pan. Brush lightly with butter and sprinkle with cornmeal. Let rise until double, 50 to 60 minutes. Bake at 400° for 25 to 30 minutes. Remove from pan. Cool on wire rack.