Homotrimer or heterotrimer. Specifically expressed in the testis and ovary in adult tissues. At 9.5 dpc it is expressed in the somites and in mesenchymal cells of the head and the branchial arches. At 14.5 dpc it is expressed in the surrounding mesenchyme of the kidney and the inner ear. Expression is also observed in the spinal nerves and ganglia, the mesenchyme of the skull, the diaphragm, and the skeletal muscles. Hydroxylated on proline residues. N-glycosylated. May be due to a competing acceptor splice site.