How to cite conference contribution that appears later in a Journal Supplement People from our group attended some important conferences (Annual Meeting of the Biophysical Society, etc) and sent abstracts that were accepted as posters or talks. Later, the abstract appears in a Supplement of a Journal (in this case, Biophysical Journal). 

My question is, in such cases, can one cite this publication in the CV as a regular paper? Otherwise, what should be the best way to cite it?
They are not usually listed on the same list as “regular papers” in a CV. The reason for that is that they are not peer-reviewed. In the fields of physics, chemistry and biology, it is most common to list your scientific production in a CV by breaking it down into the following categories:


Peer-reviewed articles
Book chapters
Conference proceedings
Invited conference talks
Conference talks
Conference posters


I looked at examples from the Biophysical journal supplements, and the abstracts are quite short (one paragraph or two). Even though it is published in print, it is too short to be considered proceedings. Thus, I would list it as either a talk or a poster. That is was published as part of a supplement to one journal does not make it very different from any other conference.

In some countries and in some fields, it may also be typical to further break down between national and international venues (journals, conferences, etc.).



As a side note, the journal webpage has some information on how to format such citations:


  Smith, R., S.E. Jones, T.J. Smith, (2006) Histone phosphorylation in DNA damage. 2006 Biophysical Society Meeting Abstracts. Biophysical Journal, Supplement, Abstract.