C3G is expressed ubiquitously in embryos with stronger expression in the founder cells of the developing visceral mesoderm. It is also observed in the visceral mesoderm at later stages, in somatic muscle and in the CNS.

C3G transcript expression is detected starting at embryonic stage 4, with low levels throughout the embryo, and high levels at the anterior and posterior poles. A moderate level of expression is detected in all tissues throughout embryonic development, with higher levels of expression in some tissues. At stage 11, levels are high in the visceral mesoderm. At late stage 14, a segmentally repeated pattern of expression becomes apparent. Expression is also detected in the hindgut and foregut.