PROS1 and obesity due to melanocortin 4 receptor deficiency: Interestingly, these changes were associated with a shift in markers of muscle properties, since fast muscle proteins, such as myosin light chain (MYL) 1, myosin regulatory light chain 2 (MYLPF), and fast skeletal muscle troponin-I (TNNT3), were upregulated, whereas slow muscle proteins, such as other myosin light chain isoforms (MYL2, MYL3) and slow skeletal muscle troponin-T (TNNT1), were downregulated in obesity and T2D [101].