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The channel has a large diameter of 0.8x1.1nm, and is non-selective for small ions. However, it has an upper exclusion size limit corresponding to molecular weights of about 600 Dalton of permeants. Because most metabolites have molecular weights lower than 600 Da and have been shown to pass through porin channels, porins are called general diffusion pores.
Ion channels come in many different types, some of which are selective for specific types of ions such as K+, Na+, and Ca2+. Â© 2002 Nature Publishing Group Marban, MarbÃ¡n. E cardiac. channelopathies