Ion channels are proteins which sit in the membrane of every cell in the body and control the flow of positively charged ions such as sodium and potassium into and out of the cell. The traditional view is that an ion channel exists in one of two stochastic states i.e. open or closed. However, this is challenged by the observation of intermediate conductance, or ‘subconductance’, states in a number of ion channels, including several potassium (K+) channels. It has previously been shown that heteromeric XTKir4.1/XTK5.1 channels are a model system for observing the usually short-lived subconductance levels [1]. These particular channels exhibit long-lived subconductance states and that an ortholog of Kir5.1 from Xenopus tropicalis causes a dramatic change in the frequency and duration of these substates. It is theorised that these sublevels correspond to the movement of the individual subunit which form the channel. In this study we used the different pieces of available software [2-4] to details the kinetic analysis on this model system, based on my experimental data gathered using single channel recording [Fig1,2]. Figure 1 Single-channel recording of the rat Kir4.1-Kir5.1 channel. The S1 and S2 subconductance states are visible in an expanded trace on the right. Figure 2 Left Hand Panel: Single channel currents from the X.tropicalis XTKir4.1/XTKir5.1 heteromeric channel showing the extended duration of the S1 sublevel state. Right Hand Panel: This long S1 sublevel duration is also observed with the ratKir4.1 subunit therefore the difference is due to the presence of the XTKir5.1 subunit. In both dimers all four conductance levels are visible. For the measurement of subconductance states in all type of channels we used the threshold-crossing method, amplitude histograms and HMM (Hidden Markov Model) analysis. Single-channel events were analyzed first by idealizing the recording into closed and open dwells, and then fitting histograms of dwell times with mixtures of exponential functions that reflect the dwells in various states using Clampfit 9.2 and HJCFIT software. To ensure the unambiguous detection of brief sublevel events and comparison of sublevel durations we will use QuB analysis software. A combination of amplitude histograms and dwell time analysis under different analysis software have been compared and contrasted to build a mathematical model to show how many sublevel states exist is formed and to gain some insight into its mechanism.