Efficient　strategies　for　enriching　and　separating　proteins　are　important　and　challenging　for　membrane　proteomics.　Many　existing　methods　are　caught　in　the　dilemma　of　preserving　maximal　membrane　proteins　while　avoiding　the　contamination　of　cytoplasmic　proteins　and　organelles.　Here,　we　report　a　polymer　anchoring　strategy　for　the　selective　preparation　of　membrane　proteins　through　cell　surface-initiated　atom　transfer　radical　polymerization.　The　cytocompatible　polymerization　strategy　enables　thermoresponsive　poly(N-isopropylacrylamide)　(pNIPPAm)　chains　to　be　grown　from　a　specific　protein　on　the　surface　of　living　cells.　The　polymer　tagged　membrane　protein　could　be　easily　separated　and　enriched　by　thermoprecipitation.　This　method　led　to　the　identification　of　1825　proteins　of　which　1036　(71.7%)　were　specific　membrane　proteins　in　E.　coli.　The　separated　proteins　were　identified　by　2-DE　and　mass　spectrometry.　Among　the　12　protein　spots　from　the　gel　slice,　eight　were　identified　as　outer　membrane　proteins.　The　described　strategy　opens　up　a　new　avenue　for　membrane　protein　enrichment　and　separation　and　may　expedite　the　future　development　of　membrane　proteomics.