ASSOCIATION OF A 14-3-3 PROTEIN WITH CMP-NEUAC-GM1 ALPHA-2,3-SIALYLTRANSFERASE

CMP-NeuAc:GM1 alpha 2,3-sialyltransferase (ST-IV) was purified to homo geneity from rat: brain. Microsequencing of the tryptic peptides deriv ed from the purified enzyme revealed two amino acid sequences homologo us to the 14-3-3 proteins. A polyclonal antibody was raised against pu rified ST-IV. A 33 kDa protein was co-immunoprecipitated from rat brai n extracts with the anti-(ST-IV) antibody as detected by Western blot analysis. This protein was identified as a subtype of 14-3-3 family by an anti-(14-3-3) antibody. Screening of a rat brain lambda gt11 libra ry using the anti-(ST-IV) antibody resulted in the identification of a cDNA clone coding for the subtype of 14-3-3 protein. These results in dicate an association of the 14-3-3 protein with the sialyltransferase . Since the 14-3-3 protein has PKC inhibitor activities and the activi ty of sialyltransferases is, at least in part, regulated by PKC, the a ssociation of the 14-3-3 protein with ST-IV may indicate a role for th is protein in the post-translational regulation of the sialyltransfera se activity through the processes of phosphorylation and dephosphoryla tion. (C) 1996 Academic Press, Inc.