A　protein　with　a　molecular　mass　of　85　kDa　and　an　N-terminal　sequence　resembling　polymeric　immunoglobulin　receptor　has　been　isolated　from　bovine　milk.　The　isolation　procedure　involved　removal　of　globulin　from　acid　whey　by　precipitation　with　1.8　M　(NH4)(2)SO4　followed　by　addition　of　(NH4)(2)SO4　to　attain　a　concentration　of　3.6　M.　Subsequent　steps　included　chromatography　on　CM-Sepharose　and　Mono　S　and　elution　of　the　protein　of　interest　with　a　linear　NaCl　concentration　gradient.　The　polymeric　immunoglobulin　receptor-like　milk　protein　inhibited　HIV-1　reverse　transcriptase　(RT)　with　an　IC50　of　4.8　muM.　However,　it　did　not　exhibit　ribonuclease　activity.　Neither　did　it　inhibit　translation　in　a　cell-free　rabbit　reticulocyte　lysate　system.　(C)　2004　Elsevier　Ltd.　All　rights　reserved.