I'm no expert, but it seems to me that as long as there is still basic research being done on the behavior of very simple proteins, we're a long way from understanding the complex interactions that happen in cells.
Yes we have a lot to learn about all the interactions between proteins in a cell, but this typically does not fall under the heading of biochemistry.
Slightly off topic the traditional divisions between different areas of biological sciences that built up in the 20th C have all broken down with the rise of molecular biology. Once biochemistry was a different field to say microbiology, now both are part of the super-field of molecular sciences.
