The invention relates to G protein-coupled receptor (GPCR) microarrays on porous substrates for structural or functional analyses of GPCRs, and methods of preparing porous substrate surfaces for receiving membranes that comprise GPCRs. In one embodiment, a GPCR microarray of the invention comprises a membrane adhered to an upper surface of a porous substrate, the membrane spanning across a plurality of pores on the porous substrate to form a plurality of cavities having sufficient geometry to permit entry of assay reagents into each cavity, thereby allowing access of assay reagents to both sides of GPCR in the membrane.