The bigger band corresponds to the protein core size and the smaller possibly to a degradation product or a shorter isoform. In the loss of function mutants agr-1 and agr-1 we expected a complete lack of the protein, but agr-1 carrying an in-frame deletion and was expected to express a shorter protein. However, in the agr1 mutant the deleted exons 26 and 27 encode the majority of the region against which the polyclonal antibodies were raised. Therefore, this truncated protein may not be recognized and no band detected even though the protein may be expressed. Another possibility is that the protein with the deletion does not fold Trometamol properly and gets degraded. In any case, it is clear that the agrin mutants do not express the normal agrin protein as the wild type worms do. Interestingly, vertebrates express proteins that share high similarity to CAM-1 and LEV-10, suggesting that these novel factors discovered in the worm could have been conserved during evolution. Thus, both CAM-1 and LEV-10 may be components of distinct pathways important for AChR clustering in nematodes that may have been complemented by the agrin-MuSK pathway during evolution in vertebrates. We then took a closer look at the sites of agrin expression visualized by reporter genes and antibody staining. Prominent expression was found in four head neurons and some pharyngeal cells. This relatively restricted expression pattern was confirmed by several reporter constructs with varying portions of the gene as well as by antibody staining. We identified the four VU 0364770 agrin-expressing neurons by injecting agr1::dsRED construct into the transgenic lines expressing GFP in specific neuron subtypes. This approach identified the agrinexpressing neurons as inner labial sensilla polymodal neurons. These are mechanosensory neurons, motoneurons and interneurons at the same time. There are six IL1 neurons in total in the head of the worm, but agrin was found to be expressed only in the dorsal and ventral pairs. Such a sub-specialization might be significant to distinguish very fine sensory inputs from the environment.