The biosynthesis of ubiquitin by parathyroid gland

Data are presented on the isolation, biosynthesis, and identification of a small peptide (H) from parathyroid gland. Under our experimental conditions this peptide (H) represents, in addition to secretory protein-I and proparathyroid hormone, the other major protein which is rapidly synthesized during shorterm incubations of tissue slices. N-terminal sequence analysis was performed on samples of peptide H and the resulting data used to conduct a search of the sequence data bank. The search established the identity of peptide H as ubiquitin. These findings establish parathyroid gland as another system which rapidly produces ubiquitin $\text{in}$$\text{vitro}$, in addition to the systems employing hypothalamus and pituitary where ubiquitin biosynthesis was initially observed by Seidah $\text{et}$$\text{al}$ and Scherrer $\text{et}$$\text{al}$.