indefinite article - "Part of the team" vs. "a part of the team"

I see both of these are used:

• 
  

  I'm part of Acme's technical team.

  
  


• 
  

  I'm a part of Acme's technical team.

  
  

Which one sounds more natural when introducing myself in an email? Is "Part" countable or uncountable in this context?

Answer

As a statement by itself,

I'm part of Acme's technical team.

is more natural.

But you could use an article as emphasis or when contrasting with other information.

He is a part of Acme's technical team, even though he does not contribute much.

(after making a big contribution) You see, I am a part of Acme's technical team.