This paper discusses how どうも is used. On page 216, the following sentence shows up.
「どうも」は、これらの文表現において、一話部をになっている。
文表現 here refers to the expressions, "Thank You" "Sorry" "Excuse Me" "thank you for coming" "sorry to take your time" "Hello" and "Goodbye". I am having a hard time figuring out what 一話部 means. I'm guessing it means "part of a sentence", but am not sure.
Does 一話部をになっている mean that the word どうも is a part of those sentences in Japanese? Or simply that it carries the meaning of some of those expressions?