LINKAGE OF 17-BETA-ESTRADIOL DEHYDROGENASE TO ACTIN BY EPSILON-(GAMMA-GLUTAMYL)-LYSINE IN PORCINE ENDOMETRIAL CELLS

We report on the discovery of interactions of porcine endometrial 17beta-oestradiol dehydrogenase with actin. The 17beta-oestradiol dehydrogenase of porcine uteri is an essentially unidirectional enzyme compounded in specialized organelles. The enzyme activity in Brij 35 extracts of the particulate fraction of epithelial cells sedimenting between 1800 and 11 000 g(av). was collected by immunoadsorption and eluted at low pH. The eluate contained three proteins of 32, 45 and 80 kDa as shown by SDS/PAGE and silver staining. They were identified by amino acid sequencing and immunotyping as oestradiol dehydrogenase (32 kDa), actin (45 kDa) and a covalent dehydrogenase-actin complex (80 kDa). Disulphides, aldimines, periodate-degradable bonds and hydrophobic interactions were excluded as linkages in the 80 kDa protein. The epsilon-(gamma-glutamyl)-lysine nature of the covalent crosslink was recognized by narrow-bore h.p.l.c. analysis of enzymic digests of electroeluted 80 kDa material. An involvement of the actin anchor in positioning of the oestradiol dehydrogenase-containing organelles according to metabolic requirements is discussed.