The difference between growth factors and transcription factors might be a nonissue for many researchers, but after Google searching, I have discovered that the question does exist within our field.

My introduction to transcription factors came from my undergrad developmental biology class. The problem is that my professor classified both growth factors and transcription factors, all as transcription factors. And since this was my first time learning about it, there was no reason to question his lecture. I must also admit that my textbook either did not do a great job defining the difference, or I just wasn’t looking for it. For me, things like fibroblast growth factors all fell under transcription factors. I didn’t consider them to be synonymous; instead, I thought growth factors were simply a subcategory.

It wasn’t until coming to GoldBio that I began to question the possibility of a difference between the two. I’m not alone in this revelation, which is why I think it’s important to highlight the defining differences.

Transcription Factors: Transcription factors are molecules that can bind either directly or indirectly to a DNA sequence and regulate the transcription of a particular gene or set of genes. They function in concert with other proteins, either blocking or promoting RNA polymerase. Transcription factors also have at least one, but sometimes more, DNA binding domains that allows them to attach to specific sequences or to DNA near the gene being regulated.

Growth Factors: Growth factors are generally molecules that are secreted and interact with other molecules or specified receptors to influence cellular behavior, including cell differentiation, healing and cell proliferation.

Key Difference: The major difference is that transcription factors bind to DNA while growth factors do not. Instead of binding to DNA, growth factors interact with other cellular molecules.

The Relationship: Part of the natural confusion comes from the relationships that exist between the two. As you learn about different signaling pathways, the primary goal when you’re first introduced to the topic is to understand the interaction between molecules and proteins within a particular cascade. Once you wrap your head around that, it’s easy to overlook some of the physical and chemical differences that exist between each player.

In a given pathway, a growth factor is secreted by a cell. It then binds to its cell surface receptor, and that interaction catalyzes a chain of actions within the cell. Binding leads to signal transduction until finally a transcription factor is activated, or a cell’s growth behavior is influenced.

Naturally, that means that all the interactions must be especially fine-tuned for optimal performance. This is why we see horrible developmental disorders or cancers when a particular protein is mutated. Blocking part of a pathway can lead to a disruption in the whole process.

So now the confusion is dispelled. Perhaps you didn’t even know you were confused.