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Why are some protein complexes composed of many different types of proteins? How many different types are they composed of? In particular, which protein complex has the greater number of different types of proteins in it?

For example, I've read that the ribosome consists of 70-80 different types of proteins.

How many different types of proteins are in the spliceosome for example?

I'm using the phrasing "types of proteins" to distinguish aggregates/complexes composed of many different copies of the same protein (i.e. some viral capsids) from those composed of many different kinds (i.e. ribosome, exosome complex, spliceosome).

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    $\begingroup$ it is better to say "70-80 different proteins". Saying types impose that there is a classification. They are just different proteins aka polypeptides $\endgroup$ – aaaaa says reinstate Monica Apr 25 '15 at 20:23
  • $\begingroup$ I've edited your question to include suggestion by @aandreev. Please feel free to revert at any time. $\endgroup$ – Nandor Poka Apr 25 '15 at 20:37
  • $\begingroup$ thanks for the criticism @aandreev. I edited the question to try to clarify why I used "types." Is there a more appropriate terminology to use? $\endgroup$ – Jesse W. Collins Apr 25 '15 at 21:56
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In this paper detailed analysis has been made on spliceosome (U2-type) composition. It should be noted that this complex has dynamic composition. In the paper authors state that up to 170 proteins may associate to a metozoan spliceosome during its course of action. Individual assemblies contain approx 110 proteins (human). Similar complex of the yeast contains approx 60 proteins (precatalytic B complex), while C complexes have 50 proteins, altogether 90 different were identified in yeast. See the linked paper for details.

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