Table 2. Amidated route: estimates of NMNAT isozymes' physiological activity.
| NMNAT1a | NMNAT2a | NMNAT3a | Total NMNAT | |
| nmol/min/g | nmol/min/g | nmol/min/g | nmol/min/g | |
| skeletal muscle | 1.12 | nd | nd | ∼1.1 |
| lung | 0.64 | nd | nd | ∼0.6 |
| kidney | 14.1 | nd | 0.57 | ∼15 |
| brain | 0.73 | 0.14 | nd | ∼0.9 |
| spleen | 1.14 | nd | 0.051 | ∼1.2 |
| small intestine | 1.70 | nd | nd | ∼1.7 |
| heart | 4.17 | nd | 0.97 | ∼5.1 |
| liver | 19.5 | nd | 0.90 | ∼20 |
| blood | 0.0054 | nd | 0.0035 | ∼0.009 |
a
Values are calculated from the steady-state kinetic equation (2) described in Methods, using the NMNAT isozyme activities measured at saturating substrates (Figure 3C) as V max values, the NMN and ATP levels (nmol/g, Figure 4) as micromolar concentrations, and the K m values from [18]; nd, not detectable.