The invariant chain is a glycoprotein transiently associated with the alpha and beta subunits of class II antigens of the major histocompatibility complex during their transport to the cell surface. An expression assay with cDNA clones transfected into simian COS cells was used to test whether the invariant chain is required for assembly and transport of human class II antigens. COS cells do no...

Partially supported by NSERC grant OGP-0121848 and European Community grant CHBGT-CT93-0244. The existence of an invariant surface in high-dimensional systems greatly influences the behavior in a neighborhood of the invariant surface. We prove theorems that predict the behavior of periodic orbits in the vicinity of an invariant surface on which the motion is conjugate to a Diophantine rotation ...