  We study multivariable (bilateral) basic hypergeometric series associated
with (type $A$) Macdonald polynomials. We derive several transformation and
summation properties for such series including analogues of Heine's
${}_2\phi_1$ transformation, the $q$-Pfaff-Kummer and Euler transformations,
the $q$-Saalsch\"utz summation formula and Sear's transformation for
terminating, balanced ${}_4\phi_3$ series. For bilateral series, we rederive
Kaneko's analogue of the ${}_1\psi_1$ summation formula and give multivariable
extensions of Bailey's ${}_2\psi_2$ transformations.
