Pseudorandom binary sequence

I have been using PN Sequences to spread input binary signals in direct sequence CDMA technique. Whenever the incoming data bit into a source is zero, it is considered as -1 and multiplied with the PN sequence of that source. My question is, if there is a zero on the PN sequence itself, e.g. [-1 +1 0 +1], does that zero should also be made -1? What about [+1 +1 0 0 0 +1] as a PN sequence, where this is no -1 entries? Should I consider the zero entries as -1?

Thank you.