We present an analysis of the binary and physical parameters of a unique pulsating white dwarf with a main-sequence companion , SDSS J1136+0409 , observed for more than 77 d during the first pointing of the extended Kepler mission : K2 Campaign 1 . Using new ground-based spectroscopy , we show that this post-common-envelope binary has an orbital period of 6.89760103 ( 60 ) hr , which is also seen in the photometry as a result of Doppler beaming and ellipsoidal variations of the secondary . We spectroscopically refine the temperature of the white dwarf to 12 330 \pm 260 K and its mass to 0.601 \pm 0.036 M _ { \odot } . We detect seven independent pulsation modes in the K2 light curve . A preliminary asteroseismic solution is in reasonable agreement with the spectroscopic atmospheric parameters . Three of the pulsation modes are clearly rotationally split multiplets , which we use to demonstrate that the white dwarf is not synchronously rotating with the orbital period but has a rotation period of 2.49 \pm 0.53 hr . This is faster than any known isolated white dwarf , but slower than almost all white dwarfs measured in non-magnetic cataclysmic variables , the likely future state of this binary .