J 16: An apex protein associated with juvenility of Sequoiadendron giganteum. 
Shoot apex proteins from 11 seedlings, two juvenile clones and three mature grafted clones of Sequoiadendron giganteum (Lindl.)  Buchh.  were examined throughout the year by SDS-polyacrylamide gel electrophoresis.  A membrane-associated protein known as J 16, with an approximate molecular weight of 16 kD, was always detected in juvenile tissue, but was absent in tissue of the mature clones.  The J 16 protein was also present in extracts of a mature clone that had been morphologically rejuvenated by micrografting.  Protein extracts from the rejuvenated clone, were separated by electrophoresis and assayed for J 16 using an immunoblotting procedure with anti-J 16 serum.  This test revealed two bands, J 16 and another protein with a lower molecular weight.  The small molecular weight protein was not detected in juvenile clones.