Members of a family of highly conserved proteins, termed 14-3-3 protei
ns, were found by several experimental approaches to associate with Ra
f-1, a central component of a key signal transduction pathway. Optimal
complex formation required the amino-terminal regulatory domain of Ra
f-1. The association of 14-3-3 proteins and Raf-1 was not substantiall
y affected by the activation state of Raf.