  Near-threshold $p\bar\Lambda$ mass spectra for the reactions $e^+e^- \to K^-
p\bar\Lambda$ and $J/\psi \to K^- p\bar\Lambda$ are investigated with an
emphasis on the role played by the interaction in the $p\bar\Lambda$ system. As
guideline for the $p\bar\Lambda$ interaction a variety of $\Lambda\bar\Lambda$
potential models is considered that have been established in the analysis of
data on $p\bar p\to \Lambda\bar\Lambda$ in the past. Arguments why the
properties of the $p\bar\Lambda$ and $\Lambda\bar\Lambda$ interactions can be
expected to be very similar are provided. It is shown that the near-threshold
enhancement in the invariant mass observed for the $e^+e^-$ reaction can be
reproduced quantitatively by the assumed $p\bar\Lambda$ final-state interaction
in the partial wave suggested by an amplitude analysis of the experiment. The
effect of the $p\bar\Lambda$ final-state interaction in other decays is
explored, including the recently measured reactions $B^- \to J/\psi\, \bar p
\Lambda$ and $B^+ \to J/\psi\, p \bar\Lambda$. It is found that the final-state
interaction improves the description of the measured invariant mass near
threshold in most cases.
