Ovocleidin (OC 116) is present in avian skeletal tissues.

Ovocleidin (OC-116), a protein identified in eggshell matrix, was found to be expressed in avian growth plate chondrocytes. Because OC-116 has been reported to be a member of a family of related phosphoprotein genes clustered on avian chromosome 4, we expanded our search to other skeletal tissues. Using Western blotting, we found OC-116 in the matrix of chick cortical bone and laying hen medullary bone as well as in hypertrophic chondrocyte lysates. Furthermore, other members of this family (bone sialoprotein, dental matrix protein-1, and osteopontin) were also present in the eggshell matrix. Reverse transcription-PCR was used to confirm the presence of the OC-116 gene in bone tissues as well as the expression of bone sialoprotein and dental matrix protein-1 in uterine tissue. These results, in combination with those of other laboratories, show that this family of phosphoproteins is found in a wide variety of avian mineralized tissues.