Fig. 3: The β4 homotetramer and the α2β2 heterotetramer.
From: Architecture and activation of human muscle phosphorylase kinase
a The β4 tetramer structure. The five domains of β1 are shown in blue and green, whereas the other three β-subunits are shown in grey. The farnesyl groups are highlighted in magenta. b Mass spectrometry analysis suggests that Cys1220 in the α-subunit is farnesylated. c Cys1090 in the β-subunit is also farnesylated. d Substituting Cys1090β with Ala leads to a shift of the PhK holoenzyme to a lower molecular weight position on size-exclusion chromatography. The elution volumes of two molecular weight standards are indicated. This experiment has been repeated three times. e Structure of the α2β2 heterotetramer. The five domains of the two α-subunits are shown in yellow and orange. One β-subunit is shown in blue and green, whereas the other is in grey.
