Texas Business Organizations Code - BUS ORG § 21.213. Enforceability of Restriction on Transfer of Certain Securities

(a) A restriction placed on the transfer or registration of the transfer of a security of a corporation is specifically enforceable against the holder, or a successor or transferee of the holder, if:

(b) Unless noted in the manner specified by Subsection (a) with respect to a certificate or other instrument or an uncertificated security, an otherwise enforceable restriction is ineffective against a transferee for value without actual knowledge of the restriction at the time of the transfer or against a subsequent transferee, regardless of whether the transfer is for value.  A restriction is specifically enforceable against a person other than a transferee for value from the time the person acquires actual knowledge of the restriction's existence.