Okla. Stat. tit. 64, § 1086

Any instrument, easement, contract, or deed which may be required in, or convenient to, the exercise of the powers granted in Section 1 of this act shall be executed by the chairman or presiding officer and attested by the secretary, if such instrument be executed by a board or commission, and if such instrument be executed by an officer, it shall be signed by said officer. No such contract, easement, deed or instrument of conveyance shall be effective unless and until the approval of the Governor is endorsed thereon in writing.