In this article two questions are discussed with regard to semiosis in protein biosynthesis for nano engines. (1) What kind of semiosis is involved in the construction of these proteins? and (2) How can we explain the semiotic process observed? With regard to the first issue we draw attention to comparisons between semiosis in protein biosynthesis and human natural language. The notion of normativity appears to be of great importance for both. A comparison also demonstrates differences. Nevertheless, because of the (...) normative symbolic information processing in it, we suggest to employ the term symbolic reference (employed in linguistics as a distinguishing feature of human language) to indicate the semiotic processes in protein biosynthesis. With regard to explaining semiosis in protein synthesis we compare different approaches. We conclude that a Kantian approach should be preferred. In such an approach strengths of the mechanistic and organicist approaches can be combined, and the observed symbolic information processing acknowledged. (shrink)