Differential subcellular localization of the survival motor neuron proteinin spinal cord and skeletal muscle

To compare the expression pattern of the survival motor neuron (SMN) protei n in spinal cord and skeletal muscle, we generated a sheep polyclonal antib ody against a bacterially expressed human SMN-fusion protein. On Western bl ots, the affinity purified anti-SMN antibody recognized a similar to 38 kDa protein band in extracts prepared from the mouse skeletal muscle, spinal c ord, and brain that co-migrated with the bacterially expressed SMN protein. In immunohistochemical studies, the anti-SMN antibody labeled mostly the c ytoplasm of the motor neurons in the anterior horn of mouse spinal cord. In contrast, predominant uniform labeling of the nuclei was observed in the m ouse skeletal muscle. Thus, our results for the first time demonstrate that the SMN protein is differentially localized in mouse spinal cord and skele tal muscle. (C) 1999 Academic Press.