X0306 4 2015-03-11 0 0001559053 Prothena Corp plc PRTA 0001564371 Schenk Dale B. C/O PROTHENA BIOSCIENCES INC 650 GATEWAY BOULEVARD SOUTH SAN FRANCISCO CA 94080 1 1 0 0 President and CEO Ordinary Shares, par value $0.01 per share 8211 I By Trust Stock Option (right to buy) 27.81 2015-03-11 4 A 0 150000 0.00 A 2025-03-11 Ordinary Shares 150000 150000 D The shares are held by the Schenk Family Trust, dated 2/9/2004, of which Reporting Person is a Co Trustee with his spouse. The shares subject to the option will vest and become exercisable as to 25% of the total number of shares subject to the option on March 11, 2016 and with respect to 1/48th of the total number of shares subject to the option in successive, equal monthly installments on each monthly anniversary thereafter, subject to the Reporting Person's continued employment with the Issuer on each such vesting date. /s/ A.W. Homan, as Attorney in Fact for Dale B. Schenk 2015-03-12