Preheat the oven to 350°F. Thoroughly grease a 10-inch nonstick bundt pan with shortening or butter followed by a light coat of flour.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, beat the butter until smooth (3-4 min.). Add granulated sugar and beat for 2-3 minutes until fluffy.
Beat eggs into the butter mixture one at a time, beating well after each addition. Add orange juice, zest, vanilla, and sour cream. Mix until fully combined.
Add the flour mixture in 3 additions, alternating with the buttermilk, begining and ending with the flour mixture. Mix just until ingredients are fully combined.
In a small bowl, toss the cranberries in flour until evenly coated. Then, gently fold them into the batter with a rubber spatula.
Pour the batter into the greased bundt pan and bake for 50-55 minutes, or until a toothpick comes out clean. Let the cake cool for 15-20 minutes in the pan. Then, carefully transfer the cake from the pan to a cooling rack to cool completely.