Chapter 7 - The Membrane Decades

Summary

In the early 1970s, even as the functional tyrosine suppressor tRNA gene was being synthesized in his laboratory, Khorana began seriously considering moving on from DNA. He was not alone among prominent researchers in molecular biology—we must remember that he did not call himself a molecular biologist—looking for research pastures beyond DNA, areas in which it was likely that there still was low-hung fruit to gather. Crick moved on to study consciousness. Nirenberg also moved on to neurobiology, to the study of neuroblastomas (tumors in the nervous system), a field to which he eventually made important contributions.

Khorana was also attracted by the prospect of a molecular neurobiology. That he chose to focus on membrane proteins seems to have been partly due to the influence of Efraim Racker, an Austrian-born biochemist, whose laboratory he visited at Cornell University in 1973. He set up a collaboration with Racker, which began with rather modest expectations. As he explained later:

[N]ucleic acids had been my focus for more than 25 years. The work on the total synthesis of genes and their cloning […] had still to be completed but the strategies seemed clear. While I was not about to say farewell to nucleic acids, the idea of starting anew in an entirely new field began to take hold in the early seventies. I began to think about biological membranes with the distant hope that I might get into areas of molecular neurobiology and signal transduction [conversion of signals from one form to another]. As in all my previous work, I did not believe that I would be able to formulate at the outset a specific area of major commitment. Rather I hoped that clarity and specific objectives would evolve in due course.

That Khorana should turn his attention to membranes in the context of the early 1970s is not very surprising. They were becoming fashionable for a variety of reasons.

Most importantly, membranes surrounded all living cells. They seemed to be the locus of many physiological activities including energy production. Protein molecules within them were implicated in signal transduction.