  We have detected redshifted CO (2-1) emission at 43 GHz and radio continuum
emission at 1.47 and 4.86 GHz from the z = 4.4 QSO BRI 1335-0417 using the Very
Large Array. The CO data imply optically thick emission from warm (>30 K)
molecular gas with a total mass, M(H_2), of 1.5+/-0.3 x10^{11} M_solar, using
the Galactic gas mass-to-CO luminosity conversion factor. We set an upper limit
to the CO source size of 1.1", and a lower limit of 0.23"x(T_ex/50K)^{-1/2},
where T_ex is the gas excitation temperature. We derive an upper limit to the
dynamical mass of 2x10^{10} x sin^{-2} i M_solar, where i is the disk
inclination angle. To reconcile the gas mass with the dynamical mass requires
either a nearly face-on disk (i < 25deg), or a gas mass-to-CO luminosity
conversion factor significantly lower than the Galactic value. The spectral
energy distribution from the radio to the rest-frame infrared of BRI 1335-0417
is consistent with that expected from a nuclear starburst galaxy, with an
implied massive star formation rate of 2300+/-600 M_solar yr^{-1}.
