I've read that myoglobin localization is responsible for the darker colour of leg muscles in turkeys. Why does this localization occur in terms of any of cell biology, molecular biology, or biochemistry? I'm not looking for bigger picture explanations at the levels of physiology or evolution, although I understand that they'll be connected to this question.


"Localization" is probably the wrong term, but I think I know what you mean... It more has to do with "expression." While the exact mechanism to my knowledge is not elucidated, it has to do with the type of motor neuron innvervating the fiber.

This has been demonstrated by studies where they cross-inervated; that is, they took the neurons which usually innervate Type I muscle fibers and innervated Type II muscle fibers with them and vice versa. The Type I fibers took on fast glycolytic properties, whereas the Type II took on the slow oxidative features (such as higher levels of mitochondria and myoglobin that you're talking about).


Sherwood L, Kell R. Human Physiology, First Canadian Edition. pp. 282-283.

  • $\begingroup$ "Localization" refers to describing, predicting, or determining the location where something is or occurs. It can also refer to the fact that something is located in particular places. I am referring to the description of where myoglobin typically occurs in turkey muscle tissue. $\endgroup$ – Galen Apr 11 '20 at 19:39
  • $\begingroup$ I'm mulling your answer over. That's quite interesting. $\endgroup$ – Galen Apr 11 '20 at 19:44
  • $\begingroup$ I think it qualifies as an answer mainly under cell biology. I'm accepting it. $\endgroup$ – Galen Apr 11 '20 at 19:45
  • $\begingroup$ Yeah it's just at least in cell bio when we talk about "localization" of a proteinusually we're talking about where it's moved to; the point of the distinction that I was making was that it's not that the myglobin is produced ubiquitously and then localized in certain cells; it's expressed at higher levels in certain types of muscle tissues. Just semantics; sorry. $\endgroup$ – rotaredom Apr 11 '20 at 19:50
  • $\begingroup$ That is semantics, but it is not just semantics. That is jargon within a specific domain. That jargon applies to this context, so I understand your desire to use it here. However, the existence of applicable jargon in a particular domain doesn't invalidate the use of more generic usages. Jargon is a fine tool, but not the only hammer. There's no universally accepted rule for deciding whether to use generic vs domain-specific language, though opinions abound, so I'm sympathic to your clarification. $\endgroup$ – Galen Apr 11 '20 at 22:54

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