 Matute was an activist in the movement against compulsory military service in Spain and the pacifist Elkarri movement.He was also a member of the Viento Sur and Ezker Gogoa foundations, and Lokarri and Euskadiko Langile Komisioak.Matute was co-ordinator for the presidency of the United Left–Greens (Ezker Batua–Berdeak, EB–B) and the federal presidency of the United Left (IU).