calcium pump. the mechanism of active transport of calcium (Ca 2+) across a membrane, as of the sarcoplasmic reticulum of muscle cells, against a concentration gradient; the mechanism is driven by hydrolysis of ATP.
A rental agreement differs from a lease agreement in that it is not a long-term contract and usually occurs on a month-to-month basis. This month-to-month lease agreement expires and then renews each month upon agreement of the parties involved.
Difference between a lease and a rental agreement. Leases and rental agreements are pretty much the same thing except for one thing: time. Rental agreements typically go from month-to-month, while leases last for a longer period of time, usually a year.