An East Coast investors group, claiming that it had its own agreement, protested the deal between parent Gates Corp. and the partnership of Cobey Corp. of Boston and Bear Stearns Cos. of New York. Gates had agreed to sell its 64.8% interest in the Tucson, Ariz.-based jet maker for $50.96 million. That would be $11.8 million less than what Gates and Cobey tentatively agreed to last year. An investor group called Avaq International claimed that Gates had reached a "binding agreement" last month that gave Avaq the exclusive right until March 13 to buy Learjet. The investor group, which includes former Midway Airlines chairman Arthur C. Bass, said in a statement that the "agreement remains in effect, and Avaq intends to take whatever action is necessary to protect its right and interest with respect to such agreement."