Markers, fluorescent spin-labels

One can place in some positions on the protein radioactive, fluorescent, or spin-labeled markers. For the same purpose one may also use antibodies and proteolytic enzymes. With these procedures one can determine those parts of the protein that are outside the membrane. Next, efforts are made to determine the position of the membrane part in the sequence. A complementary method is the hydrophobic marking of the protein by building into it hydrophobic photolabeled parts from the class of phospholipid compounds in order to determine those parts that are situated in the membrane. Another method uses proteolytic enzymes that split the protein in a specific position in the segment that is not located in the membrane. ... 

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