Heine transformations for a new kind of basic hypergeometric series in U(n)

Heine transformations are proved for a new kind of multivariate basic hypergeometric series which had been previously introduced by Krattenthaler in connection with generating functions for nonintersecting lattice paths. As a consequence, a q-Gauss and q-Chu-Vandermonde sum are proved and also a generalization of Ramanujanʹs 1ψ1 sum.