In vertebrates, the term motor neuron (or motoneuron) classically applies to neurons located in the central nervous system (CNS) which project their axons outside the CNS and directly or indirectly control muscles. The term is synonymous with efferent neurons.

ChAT (choline acetyltransferase)

• expressed in facial motor neurons. PMID: 16452675, PMID: 16382788
• synthesizes the neurotransmitter acetylcholine (ACh) and is a phenotypic marker for cholinergic neurons. PMID: 16135099
• specifically expressed by neonatal and embryonic motor neurons in vivo. PMID: 15013463
• localized predominantly within motor neurons, is a motor neuronal marker. PMID: 12744371, PMID: 2298930
• identify cholinergic DMV neurons that project into the vagus nerve. PMID: 11160606
• Somatic motor neurons begin to express the transmitter synthesizing enzyme, choline acetyltransferase (ChAT) and the low-affinity nerve growth factor receptor (NGFR) during embryonic development. PMID: 7680051

Chox10

• specific for motor neurons. PMID: 16508308

En1

• specific for motor neurons. PMID: 16508308

Even-skipped (Eve) transcription factor

• specifies dorsal motor-axon projection through the regulation of unidentified guidance molecules. PMID: 16085495

Evx1/2

• specific for motor neurons. PMID: 16508308

Fibroblast growth factor-1 (FGF1 or acidic FGF)

• highly expressed in motor neurons. PMID: 15773903

HB9

• Expressed in VA motor neurons in unc-4 mutants imposes VB-type inputs. PMID: 17289921
• a motor neuron specific marker. PMID: 17109623
• like its close relative MNR2, is expressed selectively by motor neurons (MNs) in the developing vertebrate CNS. PMID: 10482234

Isl1 ( Islet-1)

• a member of the Isl1 family of LIM-homeodomain transcription factors (LIM-HD) that is expressed in a defined subset of motor and sensory neurons during vertebrate embryogenesis. PMID: 15680372
• ISL1 is required for the generation of motor neurons and suggest that motor neuron generation is required for the subsequent differentiation of certain interneurons. PMID: 8565076
• All spinal motor neuron subtypes initially express both Isl1 and Isl2, but Isl2 is rapidly downregulated by visceral motor neurons. PMID: 14766174
• one of the earliest markers for motor neuron differentiation, is also expressed in all classes of islet cells in the pancreas. PMID: 14664703
• one of the earliest markers for motor neuron differentiation, is also expressed in all classes of islet cells in the pancreas. PMID: 14664703, PMID: 1350865

Isl2

• All spinal motor neuron subtypes initially express both Isl1 and Isl2, but Isl2 is rapidly downregulated by visceral motor neurons. PMID: 14766174

Islet1/2

• a marker specific for motor neurons. PMID: 16508308
• Motor neuron differentiation is accompanied by the expression of a LIM homeodomain transcription factor, Islet1 (ISL1). PMID: 8565076

Lim3

• specific for motor neurons. PMID: 16508308
• ventral motor neuron transcription factors. PMID: 16458285

Nkx6

• In zebrafish, Nkx6.1 is expressed in early-born primary and later-born secondary motoneurons. PMID: 15456722, PMID: 10970877, PMID: 12874134

p75(NTR) (p75 neurotrophin receptor)

• a motor neuron marker. PMID: 15378612, PMID: 15056289
• 75 kD low-affinity neurotrophin receptor, is expressed in developing and axotomised spinal motor neurons. PMID: 11276046

REG2

• a motor neuronal marker. PMID: 12744371

Sim1

• specific for motor neurons. PMID: 16508308

SMI32 (SMI-32)

• an abundant protein in motor neurons. PMID: 16049935
• a specific motor neuron marker. PMID: 15306257, PMID: 9818936
• a non-phosphorylated neurofilment marker monoclonal antibody to identify motor neurons. PMID: 14724936, PMID: 10751564, PMID: 10082077, PMID: 8753869

Zfh1

• detected in all embryonic somatic motor neurons, is a somatic motor neuron transcription factor, regulates axon exit from the CNS. PMID: 16458285