  The reactions ppbar -> e+e- and e+e- -> ppbar are analyzed in the
near-threshold region. Specific emphasis is put on the role played by the
interaction in the initial- or final antinucleon-nucleon state which is taken
into account rigorously. For that purpose a recently published NNbar potential
derived within chiral effective field theory and fitted to results of a new
partial-wave analysis of ppbar scattering data is employed. Our results provide
strong support for the conjecture that the pronounced energy dependence of the
e+e- <-> ppbar cross section, seen in pertinent experiments, is primarily due
to the ppbar interaction. Predictions for the proton electromagnetic form
factors G_E and G_M in the timelike region, close to the NNbar threshold, and
for spin-dependent observables are presented. The steep rise of the effective
form factor for energies close to the ppbar threshold is explained solely in
terms of the ppbar interaction. The corresponding experimental information is
quantitatively described by our calculation.
