Oviductin (Muc9) is expressed in rabbit endocervix

While isolating and characterizing cervical mucin glycoproteins, oviductin (Muc9) was identified in the rabbit endocervix. Following tissue homogeniza tion, endocervical proteins were fractionated by exclusion chromatography ( Sepharose CL-4B). High molecular weight components of the void volume were resolved by density gradient centrifugation using cesium bromide and dissoc iative conditions (4 M guanidinium chloride). High density fractions (rho = 1.40 1.56 g/ml) were deglycosylated with anhydrous trifluoromethane sulfon ic acid and sent to Harvard Microchemisty where in situ digestion and trypt ic peptide separation were performed. Out of an HPLC map, microsequence (KL ZMGFPTYGR) from peak 51 was 100% identical to mouse oviductin, and microseq uence (KSTGHNFPLP) from peak 70 was 90% identical to hamster oviductin. Tem poral expression of oviductin transcripts (2.4-kilobase) was negligible dur ing the first three months of postnatal cervical differentiation. Transcrip ts were minimally detectable in the cervices of 4-month-old juveniles. Stro ng expression in the endocervices of adults was eliminated by ovariectomy a nd restored by estrogen treatment. The presence of oviductin in the rabbit endocervix indicates this glycoprotein may have multiple functions, and it can no longer be considered oviduct-specific.