Can a broker also be a selling agent?

[Eugene Y.]

This question is for the rules in California.  After a person gets the real estate sales license, the licensee will hang his/her license under a licensed real estate broker, before the licensee goes out to represent the buyer or the seller.  That is understood.

My question is about the broker.  Can the broker (assume he/she also has a sales license, besides the broker license) go out to act as a sales person to represent the buyer or the seller him/herself?  

OR, the broker can only take one role at a time, i.e., either as a broker, in this case he/she hires other associate licensees to do the selling/buying, or as a sales licensee, in that case the broker can not hire other associate licensee but do the selling/buying him/herself?

Thanks to help.