CCL21 and Gitelman syndrome: However, there are examples where other membrane proteins (in particular members of the SLC family of transporters) were identified as clients of cytosolic heat shock proteins: folding of the renal NaCl transporter (SLC12A3) is for instance assisted by HSP70 and HSP90, and clinically relevant mutants that lead to Gitelman syndrome are triaged by HSP70-1A (41).