Figure 4.

sPmel17 consists of Mα and lower-molecular-weight fragment, MβN. A) Highly pigmented MNT-1 cells were metabolically radiolabeled, then chased for specific periods as noted. Cell lysates and medium were immunoprecipitated with HMB50 or NKI/beteb, separated by electrophoresis, and visualized by autoradiography. Faster-migrating bands in the medium are annotated as MβN. Asterisk indicates the nonspecific band. B) NHMs were radiolabeled and chased as described above. C) HeLa cells overexpressing an empty vector, Pmel17-i, Pmel17-l, Pmel17-is, or Pmel17-ls were radiolabeled, then chased for 3 h. Cell lysates and medium were immunoprecipitated with NKI/beteb, separated by electrophoresis, and visualized by autoradiography.