CHARACTERIZATION OF A UTERINE LUMINAL FLUID PROTEIN ULF-250 USING N-TERMINAL MICROSEQUENCING AND RT-PCR IDENTIFIES A NOVEL ESTROGEN-REGULATED GENE IN THE RAT UTERUS

We had previously identified an estrogen responsive protein ULF-250, s ynthesized and secreted by the estrous rat uterus, which is immunologi cally distinct from complement C-3 and alpha(2)-macroglobulin. The N-t erminal microsequencing of ULF-250 followed by sequence homology analy sis showed that this protein is a new member of a class of estrogen re sponsive proteins in the uterus. Polymerase chain reaction with a ULF- 250 specific primer yielded partial sequence information of its messag e. The observed pattern of ULF-250 message in the uterus during the va rious stages of the reproductive cycle in the rat suggested a possible regulation of ULF-250 message by 17 beta-estradiol. Upstream sequenci ng of ULF-250 message and its promoter domains would pro,ide insight i nto the mechanism of its regulation by estradiol.