Alerus Financial of Grand Forks, N.D., agreed to assume the assets and deposits of Prosperan Bank, while Central Bank of Kansas City is buying the assets and deposits of Gateway Bank. The failure of United Commercial Bank is expected to cost the federal deposit insurance fund an estimated $1.4 billion; the failure of the other four banks a combined $132.7 million. With United Security, 21 Georgia banks have failed this year, more than in any other state. Most of the failures have involved banks in the Atlanta area, where the collapse of the real estate market brought economic dislocation. Failures also have been especially concentrated in California and Illinois. As the economy has soured, with unemployment rising, home prices tumbling and loan defaults soaring, bank failures have cascaded and sapped billions out of the federal deposit insurance fund. It has fallen into the red. Depositors' money ¿ insured up to $250,000 per account ¿ is not at risk, with the FDIC backed by the government. The FDIC still has billions in loss reserves apart from the insurance fund. It can also tap a Treasury Department credit line of up to $500 billion.